diff --git a/README.md b/README.md
index 661074fa8..2d6131c9e 100644
--- a/README.md
+++ b/README.md
@@ -23,7 +23,8 @@ APP_COMPANY_ID=1
 
 # System Business Model (b2c/bbc)
 APP_PLATFORM=b2c
-
+  
+# Payment Callback Domain，used for payment result notifications.
 APP_CUSTOM_SERVER=
 
 # Default home page path