diff --git a/plugins/emqttd_auth_mysql/README.md b/plugins/emqttd_auth_mysql/README.md
index d6f783945..736f0fae2 100644
--- a/plugins/emqttd_auth_mysql/README.md
+++ b/plugins/emqttd_auth_mysql/README.md
@@ -2,7 +2,9 @@
 
 Authentication with user table of MySQL database.
 
-## Demo User Table
+## User Table
+
+Notice: This is a demo table. You could authenticate with any user tables.
 
 ```
 CREATE TABLE `mqtt_users` (
@@ -16,6 +18,8 @@ CREATE TABLE `mqtt_users` (
 ) ENGINE=MyISAM AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
 ```
 
-## Plugin config
+## Plugins config
+
+Please configure 'etc/plugins.config' to loade emysql and emqttd_auth_mysql plugins.
 
 
diff --git a/rel/files/plugins.config b/rel/files/plugins.config
index 737542b6b..e28dfd1c6 100644
--- a/rel/files/plugins.config
+++ b/rel/files/plugins.config
@@ -3,8 +3,8 @@
     {pool_size, 4},
     {host, "localhost"},
     {port, 3306},
-    {username, "root"},
-    {password, "public"},
+    {username, ""}, 
+    {password, ""},
     {database, "mqtt"},
     {encoding, utf8}
  ]},