一、更改my.cnf配置文件
编辑/etc/my.cnf文件，在[mysqld]下添加skip-grant-tables，保存退出。如图：
重启mysql服务：services mysqld restart
二、更改root密码
重启mysqld服务后，执行mysql命令，进入mysql命令行：
[root@yeebian ~]# mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.1.73 Source distribution Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved. Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. mysql>
修改root密码
mysql> UPDATE mysql.user SET Password=PASSWORD('mysqladmin') where USER='root';
Query OK, 0 rows affected (0.00 sec)
Rows matched: 3 Changed: 0 Warnings: 0
mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)
mysql> exit
Bye
三、删除/etc/my.cnf中的skip-grant-tables，或者注释掉，重启mysql即可。