diff --git a/src/coding/proxy/config/config.default.yaml b/src/coding/proxy/config/config.default.yaml
index 9e43ba7..05cbf4a 100644
--- a/src/coding/proxy/config/config.default.yaml
+++ b/src/coding/proxy/config/config.default.yaml
@@ -118,7 +118,7 @@ vendors:
 
 # === 故障转移触发条件 ===
 failover:
-  status_codes: [429, 403, 503, 500]
+  status_codes: [429, 403, 503, 500, 529]
   error_types:
     - "rate_limit_error"
     - "overloaded_error"
diff --git a/src/coding/proxy/config/resiliency.py b/src/coding/proxy/config/resiliency.py
index 734167c..71ba258 100644
--- a/src/coding/proxy/config/resiliency.py
+++ b/src/coding/proxy/config/resiliency.py
@@ -24,7 +24,7 @@ class RetryConfig(BaseModel):
 
 class FailoverConfig(BaseModel):
     status_codes: list[int] = Field(
-        default=[429, 403, 503, 500],
+        default=[429, 403, 503, 500, 529],
     )
     error_types: list[str] = Field(
         default=["rate_limit_error", "overloaded_error", "api_error"],
diff --git a/src/coding/proxy/vendors/base.py b/src/coding/proxy/vendors/base.py
index ef9fa6a..975d3af 100644
--- a/src/coding/proxy/vendors/base.py
+++ b/src/coding/proxy/vendors/base.py
@@ -268,8 +268,8 @@ def should_trigger_failover(
             for pattern in self._failover_config.error_message_patterns:
                 if pattern.lower() in error_message:
                     return True
-        # 429/503 即使无法解析 body 也触发故障转移
-        return status_code in (429, 503)
+        # 429/503/529 即使无法解析 body 也触发故障转移
+        return status_code in (429, 503, 529)
 
     async def check_health(self) -> bool:
         """检查供应商健康状态（轻量级探测）.
diff --git a/tests/test_vendors.py b/tests/test_vendors.py
index 97eaefd..3f2fe8c 100644
--- a/tests/test_vendors.py
+++ b/tests/test_vendors.py
@@ -650,6 +650,31 @@ def test_base_failover_without_config_returns_false():
     assert not zhipu_vendor.should_trigger_failover(503, None)
 
 
+# --- 529 overloaded_error 降级测试 ---
+
+
+def test_529_overloaded_triggers_failover():
+    """529 + overloaded_error 应触发降级（FailoverConfig 默认包含 529）."""
+    anthropic_vendor = AnthropicVendor(AnthropicConfig(), FailoverConfig())
+
+    assert anthropic_vendor.should_trigger_failover(
+        529, {"error": {"type": "overloaded_error", "message": "Overloaded"}}
+    )
+
+
+def test_529_without_body_triggers_failover():
+    """529 无 body 也应触发降级（备用安全网逻辑）."""
+    anthropic_vendor = AnthropicVendor(AnthropicConfig(), FailoverConfig())
+
+    assert anthropic_vendor.should_trigger_failover(529, None)
+
+
+def test_529_in_failover_config_default():
+    """验证 FailoverConfig 默认 status_codes 包含 529."""
+    config = FailoverConfig()
+    assert 529 in config.status_codes
+
+
 # --- _sanitize_headers_for_synthetic_response ---