修改 vim /etc/yum.repos.d/centos-base.repo如下，清华源地址为 https://mirrors.tuna.tsinghua.edu.cn/help/centos/，选择版本6，修改下面红色的2个参数。
[base] name=CentOS-$releasever - Base baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/6/os/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os gpgcheck=0 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6 #released updates [updates] name=CentOS-$releasever - Updates baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/6/updates/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates gpgcheck=0 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6 #additional packages that may be useful [extras] name=CentOS-$releasever - Extras baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/6/extras/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6 #additional packages that extend functionality of existing packages [centosplus] name=CentOS-$releasever - Plus baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/6/centosplus/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus gpgcheck=1 enabled=0 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6 #contrib - packages by Centos Users [contrib] name=CentOS-$releasever - Contrib baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/6/contrib/$basearch/ #mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib gpgcheck=1 enabled=0 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6