一，鉴于用国外的Yum源，速度比较慢，所以想到将国外的yum源，改为国内的Yum源，著名的有网易 阿里云源。如何更改呢？
二，更改yum源为网易的。
首先备份/etc/yum.repos.d/CentOS-Base.repo
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
下载对应版本repo文件, 放入/etc/yum.repos.d/(操作前请做好相应备份)
http://mirrors.163.com/.help/CentOS5-Base-163.repo http://mirrors.163.com/.help/CentOS6-Base-163.repo http://mirrors.163.com/.help/CentOS7-Base-163.repo
运行以下命令生成缓存
yum clean all && yum makecache
三，更改阿里云的yum源、以及扩展源。
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup
CentOS 5 wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-5.repo CentOS 6 wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-6.repo CentOS 7 wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
yum clean all && yum makecache
mv /etc/yum.repos.d/epel.repo /etc/yum.repos.d/epel.repo.backup
mv /etc/yum.repos.d/epel-testing.repo /etc/yum.repos.d/epel-testing.repo.backup
epel(RHEL 7) wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-7.repo epel(RHEL 6) wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-6.repo epel(RHEL 5) wget -O /etc/yum.repos.d/epel.repo http://mirrors.aliyun.com/repo/epel-5.repo
原文：http://www.cnblogs.com/lxh823/p/7073356.html