1.打开配置文件/etc/mysql/mysql.conf/mysql.cnf,在mysqld下添加一行skip-grant-tables
[mysqld] #... skip-grant-tables #...
2.重启mysql
service mysql restart
3.登陆mysql
mysql -uroot -p mysql> use mysql; update user set authentication_string=password('newpassword') where user='root';
4.修改 /etc/mysql/mysql.conf/mysql.cnf 文件,去掉skip-grant-tables
5.重启mysql
service mysql restart