diff --git a/config/mongodb.yml b/config/mongodb.yml
index 262cf6333..072cb4b8f 100644
--- a/config/mongodb.yml
+++ b/config/mongodb.yml
@@ -8,6 +8,7 @@ database: openim_v3
 username: openIM
 # Password for database authentication
 password: openIM123
+# Authentication source for database authentication, if use root user, set it to admin
 authSource: openim_v3
 # Maximum number of connections in the connection pool
 maxPoolSize: 100