diff --git a/wwwroot/docs/api_doc.ui b/wwwroot/docs/api_doc.ui
index 719ca1d7..f6c82f41 100644
--- a/wwwroot/docs/api_doc.ui
+++ b/wwwroot/docs/api_doc.ui
@@ -1,4 +1,4 @@
-{% set lang = request.args.get('lang') or 'zh' %}
+{% set lang = params_kw._lang or 'zh' %}
 {
     "widgettype": "ApiDoc",
     "options": {