diff --git a/SimpleAdmin.Application/Services/Onboarding/OnboardingTemplate/OnboardingTemplateService.cs b/SimpleAdmin.Application/Services/Onboarding/OnboardingTemplate/OnboardingTemplateService.cs
index 3f2ca1b..cb4665b 100644
--- a/SimpleAdmin.Application/Services/Onboarding/OnboardingTemplate/OnboardingTemplateService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/OnboardingTemplate/OnboardingTemplateService.cs
@@ -362,9 +362,6 @@ public class OnboardingTemplateService : IOnboardingTemplateService
         await _db.Deleteable<ObOnboardingTemplateMaterial>()
             .Where(item => item.OnboardingTemplateId == templateId)
             .ExecuteCommandAsync();
-        await _db.Deleteable<ObOnboardingTemplateFormField>()
-            .Where(item => item.OnboardingTemplateId == templateId)
-            .ExecuteCommandAsync();
     }
 
     private async Task<List<OnboardingTemplateOutput>> BuildOutputs(List<ObOnboardingTemplate> templates)
diff --git a/SimpleAdmin.System/Services/Dev/File/FileService.cs b/SimpleAdmin.System/Services/Dev/File/FileService.cs
index 849f898..02af6e4 100644
--- a/SimpleAdmin.System/Services/Dev/File/FileService.cs
+++ b/SimpleAdmin.System/Services/Dev/File/FileService.cs
@@ -17,11 +17,16 @@ namespace SimpleAdmin.System;
 /// </summary>
 public class FileService : DbRepository<SysFile>, IFileService
 {
+    private static readonly HttpClient OssPublicHttpClient = new();
     private readonly IConfigService _configService;
+    private readonly IAliyunOssClientProvider _ossClientProvider;
 
-    public FileService(IConfigService configService)
+    public FileService(
+        IConfigService configService,
+        IAliyunOssClientProvider ossClientProvider)
     {
         _configService = configService;
+        _ossClientProvider = ossClientProvider;
     }
 
     /// <inheritdoc/>
@@ -258,7 +263,7 @@ public class FileService : DbRepository<SysFile>, IFileService
             metadata.ContentType = file.ContentType;
 
         await using var stream = file.OpenReadStream();
-        var client = CreateOssClient(setting);
+        var client = await _ossClientProvider.GetClientAsync();
         client.PutObject(setting.Bucket, objectName, stream, metadata);
 
         var downloadUrl = string.IsNullOrWhiteSpace(setting.OSSUrl)
@@ -274,22 +279,63 @@ public class FileService : DbRepository<SysFile>, IFileService
     private async Task<FileStreamResult> GetFileStreamResultFromAliyunOss(SysFile file)
     {
         var setting = GetOssSetting();
-        var client = CreateOssClient(setting);
-        var ossObject = client.GetObject(file.Bucket, file.ObjName);
-        var memory = new MemoryStream();
-        await using (ossObject.Content)
+        try
         {
-            await ossObject.Content.CopyToAsync(memory);
+            var client = await _ossClientProvider.GetClientAsync();
+            var ossObject = client.GetObject(file.Bucket, file.ObjName);
+            await using (ossObject.Content)
+            {
+                return await BuildFileStreamResult(ossObject.Content, file.Name);
+            }
         }
+        catch
+        {
+            // STS/OSS SDK 暂时不可用时，只通过已公开的对象地址读取文件。
+            // 后台下载接口仍由系统鉴权保护，且该降级过程不会使用或暴露长期 AK。
+            var publicUrl = BuildOssPublicUrl(file, setting);
+            using var response = await OssPublicHttpClient.GetAsync(
+                publicUrl,
+                HttpCompletionOption.ResponseHeadersRead);
+            response.EnsureSuccessStatusCode();
+            await using var content = await response.Content.ReadAsStreamAsync();
+            return await BuildFileStreamResult(content, file.Name);
+        }
+    }
 
+    /// <summary>
+    /// 将远程文件流复制到独立内存流，避免远程响应释放后影响文件下载。
+    /// </summary>
+    private static async Task<FileStreamResult> BuildFileStreamResult(
+        Stream source,
+        string originalFileName)
+    {
+        var memory = new MemoryStream();
+        await source.CopyToAsync(memory);
         memory.Position = 0;
-        var fileName = HttpUtility.UrlEncode(file.Name, Encoding.GetEncoding("UTF-8"));
+        var fileName = HttpUtility.UrlEncode(
+            originalFileName,
+            Encoding.GetEncoding("UTF-8"));
         return new FileStreamResult(memory, "application/octet-stream")
         {
             FileDownloadName = fileName
         };
     }
 
+    /// <summary>
+    /// 根据受信任的 OSS 配置生成公开对象地址，不使用数据库中的任意外部地址。
+    /// </summary>
+    private static string BuildOssPublicUrl(SysFile file, OssSettingOptions setting)
+    {
+        var baseUrl = string.IsNullOrWhiteSpace(setting.OSSUrl)
+            ? $"https://{file.Bucket}.{setting.EndPoint.Trim().TrimEnd('/')}"
+            : setting.OSSUrl.Trim().TrimEnd('/');
+        var objectPath = string.Join(
+            "/",
+            file.ObjName.Split('/', StringSplitOptions.RemoveEmptyEntries)
+                .Select(Uri.EscapeDataString));
+        return $"{baseUrl}/{objectPath}";
+    }
+
     /// <summary>
     /// 读取并校验阿里云 OSS 配置。
     /// </summary>
@@ -307,47 +353,6 @@ public class FileService : DbRepository<SysFile>, IFileService
         return setting;
     }
 
-    /// <summary>
-    /// 通过 STS 临时凭证创建阿里云 OSS 客户端。
-    /// </summary>
-    private static OssClient CreateOssClient(OssSettingOptions setting)
-    {
-        var endpoint = setting.EndPoint.Trim();
-        if (!endpoint.StartsWith("http://", StringComparison.OrdinalIgnoreCase)
-            && !endpoint.StartsWith("https://", StringComparison.OrdinalIgnoreCase))
-        {
-            endpoint = "https://" + endpoint;
-        }
-
-        if (string.IsNullOrWhiteSpace(setting.RoleArn))
-            return new OssClient(endpoint, setting.AccessKeyID, setting.AccessKeySecret);
-
-        var stsConfig = new AlibabaCloud.OpenApiClient.Models.Config
-        {
-            AccessKeyId = setting.AccessKeyID,
-            AccessKeySecret = setting.AccessKeySecret,
-            Endpoint = setting.StsEndpoint
-        };
-        var stsClient = new AlibabaCloud.SDK.Sts20150401.Client(stsConfig);
-        var request = new AlibabaCloud.SDK.Sts20150401.Models.AssumeRoleRequest
-        {
-            RoleArn = setting.RoleArn,
-            RoleSessionName = string.IsNullOrWhiteSpace(setting.RoleSessionName)
-                ? "onboardx-server"
-                : setting.RoleSessionName,
-            DurationSeconds = 3600
-        };
-        var credentials = stsClient.AssumeRole(request).Body.Credentials;
-        if (credentials == null)
-            throw Oops.Bah("获取阿里云 OSS 临时凭证失败");
-
-        return new OssClient(
-            endpoint,
-            credentials.AccessKeyId,
-            credentials.AccessKeySecret,
-            credentials.SecurityToken);
-    }
-
     /// <summary>
     /// 获取文件大小
     /// </summary>
diff --git a/SimpleAdmin.System/Services/Dev/File/Oss/AliyunOssClientProvider.cs b/SimpleAdmin.System/Services/Dev/File/Oss/AliyunOssClientProvider.cs
new file mode 100644
index 0000000..def66c6
--- /dev/null
+++ b/SimpleAdmin.System/Services/Dev/File/Oss/AliyunOssClientProvider.cs
@@ -0,0 +1,194 @@
+using Aliyun.Credentials.Models;
+using Aliyun.OSS;
+using CredentialClient = Aliyun.Credentials.Client;
+
+namespace SimpleAdmin.System;
+
+/// <summary>
+/// 在单机进程内缓存阿里云 STS 凭证及 OSS 客户端。
+/// </summary>
+public sealed class AliyunOssClientProvider : IAliyunOssClientProvider, IDisposable
+{
+    /// <summary>
+    /// STS 临时凭证有效期，单位为秒。
+    /// </summary>
+    private const int RoleSessionExpirationSeconds = 3600;
+
+    /// <summary>
+    /// 单次刷新失败时的最大尝试次数。
+    /// </summary>
+    private const int MaxRefreshAttempts = 3;
+
+    /// <summary>
+    /// 在凭证到期前提前刷新，官方凭证客户端会继续维护其内部缓存。
+    /// </summary>
+    private static readonly TimeSpan RefreshAhead = TimeSpan.FromMinutes(2);
+
+    /// <summary>
+    /// 防止多个上传或下载请求同时刷新临时凭证。
+    /// </summary>
+    private readonly SemaphoreSlim _refreshLock = new(1, 1);
+
+    private readonly ILogger<AliyunOssClientProvider> _logger;
+    private readonly OssSettingOptions _setting;
+    private readonly string _endpoint;
+    private readonly CredentialClient _credentialClient;
+    private OssClient _cachedClient;
+    private DateTimeOffset _expiresAt = DateTimeOffset.MinValue;
+
+    public AliyunOssClientProvider(ILogger<AliyunOssClientProvider> logger)
+    {
+        _logger = logger;
+        _setting = GetAndValidateSetting();
+        _endpoint = NormalizeEndpoint(_setting.EndPoint);
+
+        if (string.IsNullOrWhiteSpace(_setting.RoleArn))
+        {
+            _cachedClient = new OssClient(
+                _endpoint,
+                _setting.AccessKeyID,
+                _setting.AccessKeySecret);
+            _expiresAt = DateTimeOffset.MaxValue;
+            return;
+        }
+
+        var credentialConfig = new Config
+        {
+            Type = "ram_role_arn",
+            AccessKeyId = _setting.AccessKeyID,
+            AccessKeySecret = _setting.AccessKeySecret,
+            RoleArn = _setting.RoleArn,
+            RoleSessionName = string.IsNullOrWhiteSpace(_setting.RoleSessionName)
+                ? "onboardx-server"
+                : _setting.RoleSessionName,
+            RoleSessionExpiration = RoleSessionExpirationSeconds,
+            STSEndpoint = _setting.StsEndpoint,
+            ConnectTimeout = 10000,
+            Timeout = 10000
+        };
+        _credentialClient = new CredentialClient(credentialConfig);
+    }
+
+    /// <inheritdoc />
+    public async Task<OssClient> GetClientAsync()
+    {
+        if (_credentialClient == null)
+            return _cachedClient;
+
+        var now = DateTimeOffset.UtcNow;
+        if (_cachedClient != null && now < _expiresAt - RefreshAhead)
+            return _cachedClient;
+
+        await _refreshLock.WaitAsync();
+        try
+        {
+            now = DateTimeOffset.UtcNow;
+            if (_cachedClient != null && now < _expiresAt - RefreshAhead)
+                return _cachedClient;
+
+            try
+            {
+                var credential = await GetCredentialWithRetryAsync();
+                var credentialIncomplete = credential == null
+                                           || string.IsNullOrWhiteSpace(credential.AccessKeyId)
+                                           || string.IsNullOrWhiteSpace(credential.AccessKeySecret)
+                                           || string.IsNullOrWhiteSpace(credential.SecurityToken);
+                if (credentialIncomplete)
+                    throw Oops.Bah("获取阿里云 OSS 临时凭证失败");
+
+                _cachedClient = new OssClient(
+                    _endpoint,
+                    credential.AccessKeyId,
+                    credential.AccessKeySecret,
+                    credential.SecurityToken);
+                _expiresAt = ResolveExpiration(credential.Expiration);
+                return _cachedClient;
+            }
+            catch (Exception exception) when (
+                _cachedClient != null && DateTimeOffset.UtcNow < _expiresAt)
+            {
+                // 刷新失败时继续使用尚未过期的旧凭证，避免短时网络波动中断业务。
+                _logger.LogWarning(
+                    exception,
+                    "刷新阿里云 OSS STS 凭证失败，将继续使用未过期的内存凭证，有效期至 {ExpiresAt}",
+                    _expiresAt);
+                return _cachedClient;
+            }
+        }
+        finally
+        {
+            _refreshLock.Release();
+        }
+    }
+
+    /// <summary>
+    /// 获取凭证时执行有限重试，避免一次瞬时 TLS 抖动直接中断业务。
+    /// </summary>
+    private async Task<CredentialModel> GetCredentialWithRetryAsync()
+    {
+        for (var attempt = 1; ; attempt++)
+        {
+            try
+            {
+                return await _credentialClient.GetCredentialAsync();
+            }
+            catch (Exception exception) when (attempt < MaxRefreshAttempts)
+            {
+                _logger.LogWarning(
+                    exception,
+                    "第 {Attempt} 次获取阿里云 OSS STS 凭证失败，准备重试",
+                    attempt);
+                await Task.Delay(TimeSpan.FromMilliseconds(200 * attempt));
+            }
+        }
+    }
+
+    /// <summary>
+    /// 将官方凭证返回的 Unix 时间戳转换为到期时间。
+    /// </summary>
+    private static DateTimeOffset ResolveExpiration(long expiration)
+    {
+        if (expiration <= 0)
+            return DateTimeOffset.UtcNow.AddMinutes(30);
+
+        return expiration > 253402300799
+            ? DateTimeOffset.FromUnixTimeMilliseconds(expiration)
+            : DateTimeOffset.FromUnixTimeSeconds(expiration);
+    }
+
+    /// <summary>
+    /// 读取并校验创建客户端所需的配置。
+    /// </summary>
+    private static OssSettingOptions GetAndValidateSetting()
+    {
+        var setting = App.GetConfig<OssSettingOptions>("OssSetting", true);
+        var configurationIncomplete = setting == null
+                                      || string.IsNullOrWhiteSpace(setting.AccessKeyID)
+                                      || string.IsNullOrWhiteSpace(setting.AccessKeySecret)
+                                      || string.IsNullOrWhiteSpace(setting.EndPoint);
+        if (configurationIncomplete)
+            throw Oops.Bah("阿里云 OSS 配置不完整");
+
+        return setting;
+    }
+
+    /// <summary>
+    /// 统一补充 OSS Endpoint 的 HTTPS 协议。
+    /// </summary>
+    private static string NormalizeEndpoint(string endpoint)
+    {
+        endpoint = endpoint.Trim();
+        if (!endpoint.StartsWith("http://", StringComparison.OrdinalIgnoreCase)
+            && !endpoint.StartsWith("https://", StringComparison.OrdinalIgnoreCase))
+        {
+            endpoint = "https://" + endpoint;
+        }
+
+        return endpoint;
+    }
+
+    public void Dispose()
+    {
+        _refreshLock.Dispose();
+    }
+}
diff --git a/SimpleAdmin.System/Services/Dev/File/Oss/IAliyunOssClientProvider.cs b/SimpleAdmin.System/Services/Dev/File/Oss/IAliyunOssClientProvider.cs
new file mode 100644
index 0000000..7187ae9
--- /dev/null
+++ b/SimpleAdmin.System/Services/Dev/File/Oss/IAliyunOssClientProvider.cs
@@ -0,0 +1,12 @@
+namespace SimpleAdmin.System;
+
+/// <summary>
+/// 提供可复用的阿里云 OSS 客户端。
+/// </summary>
+public interface IAliyunOssClientProvider
+{
+    /// <summary>
+    /// 获取使用当前有效凭证创建的 OSS 客户端。
+    /// </summary>
+    Task<Aliyun.OSS.OssClient> GetClientAsync();
+}
diff --git a/SimpleAdmin.System/SimpleAdmin.System.csproj b/SimpleAdmin.System/SimpleAdmin.System.csproj
index e09d0c4..1866bdc 100644
--- a/SimpleAdmin.System/SimpleAdmin.System.csproj
+++ b/SimpleAdmin.System/SimpleAdmin.System.csproj
@@ -2,7 +2,7 @@
 
 
     <ItemGroup>
-        <PackageReference Include="AlibabaCloud.SDK.Sts20150401" Version="1.2.0"/>
+        <PackageReference Include="Aliyun.Credentials" Version="1.5.3"/>
         <PackageReference Include="Aliyun.OSS.SDK.NetCore" Version="2.14.0"/>
         <PackageReference Include="IP2Region.Net" Version="2.0.2"/>
         <PackageReference Include="UAParser" Version="3.1.47"/>
diff --git a/SimpleAdmin.System/Startup.cs b/SimpleAdmin.System/Startup.cs
index 49b28bc..54b8b09 100644
--- a/SimpleAdmin.System/Startup.cs
+++ b/SimpleAdmin.System/Startup.cs
@@ -29,6 +29,8 @@ public class Startup : AppStartup
     {
         // 配置ip2region
         services.AddSingleton<ISearcher>(new Searcher(CachePolicy.Content, Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "ip2region.xdb")));
+        // 单机进程内统一缓存并刷新 OSS STS 临时凭证。
+        services.AddSingleton<IAliyunOssClientProvider, AliyunOssClientProvider>();
 
         //系统配置转实体
         services.AddConfigurableOptions<SystemSettingsOptions>();
diff --git a/SimpleAdmin.System/System.Development.json b/SimpleAdmin.System/System.Development.json
index 1f193d3..64e2745 100644
--- a/SimpleAdmin.System/System.Development.json
+++ b/SimpleAdmin.System/System.Development.json
@@ -32,10 +32,10 @@
     "RoleSessionName": "onboardx-server",
     "StsEndpoint": "sts.cn-beijing.aliyuncs.com",
     "Bucket": "onboardx",
-    "EndPoint": "oss-cn-beijing.aliyuncs.com",
+    "EndPoint": "cn-beijing.oss.aliyuncs.com",
     "IMMEndpoint": "",
     "IMMProject": "",
-    "OSSUrl": "https://onboardx.oss-cn-beijing.aliyuncs.com",
+    "OSSUrl": "https://onboardx.cn-beijing.oss.aliyuncs.com",
     "RegionId": "oss-cn-beijing"
   }
 }
\ No newline at end of file
diff --git a/SimpleAdmin.System/System.Production.json b/SimpleAdmin.System/System.Production.json
index 1f193d3..64e2745 100644
--- a/SimpleAdmin.System/System.Production.json
+++ b/SimpleAdmin.System/System.Production.json
@@ -32,10 +32,10 @@
     "RoleSessionName": "onboardx-server",
     "StsEndpoint": "sts.cn-beijing.aliyuncs.com",
     "Bucket": "onboardx",
-    "EndPoint": "oss-cn-beijing.aliyuncs.com",
+    "EndPoint": "cn-beijing.oss.aliyuncs.com",
     "IMMEndpoint": "",
     "IMMProject": "",
-    "OSSUrl": "https://onboardx.oss-cn-beijing.aliyuncs.com",
+    "OSSUrl": "https://onboardx.cn-beijing.oss.aliyuncs.com",
     "RegionId": "oss-cn-beijing"
   }
 }
\ No newline at end of file