1，修改MySQL的登录设置：
# vim /etc/my.cnf
在[mysqld]的段中加上一句：skip-grant-tables
例如：
[mysqld] datadir=/var/lib/mysql socket=/var/lib/mysql/mysql.sock skip-grant-tables
保存并且退出
2，重新启动mysqld
# service mysqld restart
Stopping MySQL: [ OK ]
Starting MySQL: [ OK ]
3，登录并修改MySQL的root密码
# mysql Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 3 to server version: 3.23.56 Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the buffer. mysql> USE mysql ; Database changed mysql> UPDATE user SET Password = password ( ‘new-password‘ ) WHERE User = ‘root‘ ; Query OK, 0 rows affected (0.00 sec) Rows matched: 2 Changed: 0 Warnings: 0 mysql> flush privileges ; Query OK, 0 rows affected (0.01 sec) mysql> quit
4，将MySQL的登录设置修改回来
# vim /etc/my.cnf
将刚才在[mysqld]的段中加上的skip-grant-tables删除
保存并且退出
5，重新启动mysqld
# service mysqld restart
Stopping MySQL: [ OK ]
Starting MySQL: [ OK ]
原文：http://www.cnblogs.com/lazyfang/p/7643442.html