1.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
2.下载网易的repo文件 http://mirrors.163.com/.help/CentOS6-Base-163.repo 放入/etc/yum.repos.d/(操作前请做好相应备份)
3.修改 CentOS-Media.repo，把 baseurl 改成 baseurl=http://mirrors.163.com/centos/$releasever/os/$basearch/
4.运行以下命令生成缓存
yum clean all yum makecache
原文：http://www.cnblogs.com/tswcypy/p/3930720.html