diff --git a/core/utils/web_render.py b/core/utils/web_render.py
index 4705635f08..490df9dba1 100644
--- a/core/utils/web_render.py
+++ b/core/utils/web_render.py
@@ -13,7 +13,7 @@ class WebRender:
     local = False
 
 
-def webrender(method: str = None, url: str = None, use_local: bool = True):
+def webrender(method: str = '', url: str = '', use_local: bool = True):
     '''根据请求方法生成 Webrender URL。
 
     :param method: API 方法。