diff --git a/api/.env.example b/api/.env.example
index 9cbb111d31..99cd2ba558 100644
--- a/api/.env.example
+++ b/api/.env.example
@@ -128,6 +128,7 @@ TENCENT_COS_SECRET_KEY=your-secret-key
 TENCENT_COS_SECRET_ID=your-secret-id
 TENCENT_COS_REGION=your-region
 TENCENT_COS_SCHEME=your-scheme
+TENCENT_COS_CUSTOM_DOMAIN=your-custom-domain
 
 # Huawei OBS Storage Configuration
 HUAWEI_OBS_BUCKET_NAME=your-bucket-name
diff --git a/api/configs/middleware/storage/tencent_cos_storage_config.py b/api/configs/middleware/storage/tencent_cos_storage_config.py
index e297e748e9..cdd10740f8 100644
--- a/api/configs/middleware/storage/tencent_cos_storage_config.py
+++ b/api/configs/middleware/storage/tencent_cos_storage_config.py
@@ -31,3 +31,8 @@ class TencentCloudCOSStorageConfig(BaseSettings):
         description="Protocol scheme for COS requests: 'https' (recommended) or 'http'",
         default=None,
     )
+
+    TENCENT_COS_CUSTOM_DOMAIN: str | None = Field(
+        description="Tencent Cloud COS custom domain setting",
+        default=None,
+    )
diff --git a/api/extensions/storage/tencent_cos_storage.py b/api/extensions/storage/tencent_cos_storage.py
index ea5d982efc..cf092c6973 100644
--- a/api/extensions/storage/tencent_cos_storage.py
+++ b/api/extensions/storage/tencent_cos_storage.py
@@ -13,12 +13,20 @@ class TencentCosStorage(BaseStorage):
         super().__init__()
 
         self.bucket_name = dify_config.TENCENT_COS_BUCKET_NAME
-        config = CosConfig(
-            Region=dify_config.TENCENT_COS_REGION,
-            SecretId=dify_config.TENCENT_COS_SECRET_ID,
-            SecretKey=dify_config.TENCENT_COS_SECRET_KEY,
-            Scheme=dify_config.TENCENT_COS_SCHEME,
-        )
+        if dify_config.TENCENT_COS_CUSTOM_DOMAIN:
+            config = CosConfig(
+                Domain=dify_config.TENCENT_COS_CUSTOM_DOMAIN,
+                SecretId=dify_config.TENCENT_COS_SECRET_ID,
+                SecretKey=dify_config.TENCENT_COS_SECRET_KEY,
+                Scheme=dify_config.TENCENT_COS_SCHEME,
+            )
+        else:
+            config = CosConfig(
+                Region=dify_config.TENCENT_COS_REGION,
+                SecretId=dify_config.TENCENT_COS_SECRET_ID,
+                SecretKey=dify_config.TENCENT_COS_SECRET_KEY,
+                Scheme=dify_config.TENCENT_COS_SCHEME,
+            )
         self.client = CosS3Client(config)
 
     def save(self, filename, data):
diff --git a/api/tests/unit_tests/oss/tencent_cos/test_tencent_cos.py b/api/tests/unit_tests/oss/tencent_cos/test_tencent_cos.py
index 303f0493bd..694ded0c89 100644
--- a/api/tests/unit_tests/oss/tencent_cos/test_tencent_cos.py
+++ b/api/tests/unit_tests/oss/tencent_cos/test_tencent_cos.py
@@ -1,4 +1,4 @@
-from unittest.mock import patch
+from unittest.mock import MagicMock, patch
 
 import pytest
 from qcloud_cos import CosConfig
@@ -18,3 +18,64 @@ class TestTencentCos(BaseStorageTest):
         with patch.object(CosConfig, "__init__", return_value=None):
             self.storage = TencentCosStorage()
         self.storage.bucket_name = get_example_bucket()
+
+
+class TestTencentCosConfiguration:
+    """Tests for TencentCosStorage initialization with different configurations."""
+
+    def test_init_with_custom_domain(self):
+        """Test initialization with custom domain configured."""
+        # Mock dify_config to return custom domain configuration
+        mock_dify_config = MagicMock()
+        mock_dify_config.TENCENT_COS_CUSTOM_DOMAIN = "cos.example.com"
+        mock_dify_config.TENCENT_COS_SECRET_ID = "test-secret-id"
+        mock_dify_config.TENCENT_COS_SECRET_KEY = "test-secret-key"
+        mock_dify_config.TENCENT_COS_SCHEME = "https"
+
+        # Mock CosConfig and CosS3Client
+        mock_config_instance = MagicMock()
+        mock_client = MagicMock()
+
+        with patch("extensions.storage.tencent_cos_storage.dify_config", mock_dify_config), patch(
+            "extensions.storage.tencent_cos_storage.CosConfig", return_value=mock_config_instance
+        ) as mock_cos_config, patch("extensions.storage.tencent_cos_storage.CosS3Client", return_value=mock_client):
+            TencentCosStorage()
+
+            # Verify CosConfig was called with Domain parameter (not Region)
+            mock_cos_config.assert_called_once()
+            call_kwargs = mock_cos_config.call_args[1]
+            assert "Domain" in call_kwargs
+            assert call_kwargs["Domain"] == "cos.example.com"
+            assert "Region" not in call_kwargs
+            assert call_kwargs["SecretId"] == "test-secret-id"
+            assert call_kwargs["SecretKey"] == "test-secret-key"
+            assert call_kwargs["Scheme"] == "https"
+
+    def test_init_with_region(self):
+        """Test initialization with region configured (no custom domain)."""
+        # Mock dify_config to return region configuration
+        mock_dify_config = MagicMock()
+        mock_dify_config.TENCENT_COS_CUSTOM_DOMAIN = None
+        mock_dify_config.TENCENT_COS_REGION = "ap-guangzhou"
+        mock_dify_config.TENCENT_COS_SECRET_ID = "test-secret-id"
+        mock_dify_config.TENCENT_COS_SECRET_KEY = "test-secret-key"
+        mock_dify_config.TENCENT_COS_SCHEME = "https"
+
+        # Mock CosConfig and CosS3Client
+        mock_config_instance = MagicMock()
+        mock_client = MagicMock()
+
+        with patch("extensions.storage.tencent_cos_storage.dify_config", mock_dify_config), patch(
+            "extensions.storage.tencent_cos_storage.CosConfig", return_value=mock_config_instance
+        ) as mock_cos_config, patch("extensions.storage.tencent_cos_storage.CosS3Client", return_value=mock_client):
+            TencentCosStorage()
+
+            # Verify CosConfig was called with Region parameter (not Domain)
+            mock_cos_config.assert_called_once()
+            call_kwargs = mock_cos_config.call_args[1]
+            assert "Region" in call_kwargs
+            assert call_kwargs["Region"] == "ap-guangzhou"
+            assert "Domain" not in call_kwargs
+            assert call_kwargs["SecretId"] == "test-secret-id"
+            assert call_kwargs["SecretKey"] == "test-secret-key"
+            assert call_kwargs["Scheme"] == "https"
diff --git a/docker/.env.example b/docker/.env.example
index 16d47409f5..9aa8399967 100644
--- a/docker/.env.example
+++ b/docker/.env.example
@@ -477,6 +477,7 @@ TENCENT_COS_SECRET_KEY=your-secret-key
 TENCENT_COS_SECRET_ID=your-secret-id
 TENCENT_COS_REGION=your-region
 TENCENT_COS_SCHEME=your-scheme
+TENCENT_COS_CUSTOM_DOMAIN=your-custom-domain
 
 # Oracle Storage Configuration
 #