原文地址：https://blog.csdn.net/betty_xfy/article/details/78018398
参考：https://blog.csdn.net/inslow/article/details/54177191
刚安装完的CentOS系统，默认带的yum镜像源一般都是国外的，导致在线安装的时候，速度很慢。这个时候需要你更换yum镜像源为国内的，国内主要开源的开源镜像点应该算是阿里和网易了。
**网易：http://mirrors.163.com.centos/
阿里云：http://mirros.aliyun.com/centos**
修改CentOS默认yum源为mirrors.163.com
1、备份系统自带的yum镜像源 /etc/yum.repos.d/CentOS-Base.repo
[root@betty yum.repos.d]#mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup 2、查看自己按照的centOS系统的版本
[root@betty ~]# cat /etc/system-release
CentOS release 6.7 (Final) 3、根据系统版本号，下载对应yum源配置文件到上面那个文件夹内
进入到yum源配置文件所在的文件夹
[root@betty ~]# cd /etc/yum.repos.d/ CentOS7
[root@betty yum.repos.d]# wget http://mirrors.163.com/.help/CentOS7-Base-163.repo CentOS6
[root@betty yum.repos.d]# wget http://mirrors.163.com/.help/CentOS6-Base-163.repo CentOS5
[root@betty yum.repos.d]# wget http://mirrors.163.com/.help/CentOS5-Base-163.repo 4、运行yum生成缓存
[root@betty yum.repos.d]# yum makecache 5、更新系统就能看到mirrors.163.com信息
[root@betty yum.repos.d]# yum -y update
Loaded plugins: fastestmirror, refresh-packagekit, security
Setting up Update Process
Repository base is listed more than once in the configuration
Repository updates is listed more than once in the configuration
Repository extras is listed more than once in the configuration
Repository centosplus is listed more than once in the configuration
Repository contrib is listed more than once in the configuration
Loading mirror speeds from cached hostfile
* base: mirrors.163.com
* extras: mirrors.163.com
* updates: mirrors.163.com 用阿里云，只要下载aliyun的yum配置文件到/etc/yum.repos.d/，其它步骤一致
CentOS7
[root@betty yum.repos.d]# wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
CentOS6
[root@betty yum.repos.d]# wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo
CentOS5
[root@betty yum.repos.d]# wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-5.repo