1、备份原始文件

cd /etc/yum.repos.d

mv CentOS-Base.repo CentOS-Base.repo.bak

2、修改 CentOS-Base.repo 文件

# CentOS-Base.repo

#

# The mirror system uses the connecting IP address of the client and the

# update status of each mirror to pick mirrors that are updated to and

# geographically close to the client.  You should use this for CentOS updates

# unless you are manually picking other mirrors.

#

# If the mirrorlist= does not work for you, as a fall back you can try the 

# remarked out baseurl= line instead.

#

#

[base]

name=CentOS-$releasever - Base - mirrors.aliyun.com

failovermethod=priority

baseurl=http://mirrors.aliyun.com/centos-vault/centos/$releasever/os/$basearch/

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#released updates 

[updates]

name=CentOS-$releasever - Updates - mirrors.aliyun.com

failovermethod=priority

baseurl=http://mirrors.aliyun.com/centos-vault/centos/$releasever/updates/$basearch/

gpgcheck=1

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#additional packages that may be useful

[extras]

name=CentOS-$releasever - Extras - mirrors.aliyun.com

failovermethod=priority

baseurl=http://mirrors.aliyun.com/centos-vault/centos/$releasever/extras/$basearch/

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 - mirrors.aliyun.com

failovermethod=priority

baseurl=http://mirrors.aliyun.com/centos-vault/centos/$releasever/centosplus/$basearch/

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 - mirrors.aliyun.com

failovermethod=priority

baseurl=http://mirrors.aliyun.com/centos-vault/centos/$releasever/contrib/$basearch/

gpgcheck=1

enabled=0

gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

3、清理更新缓存

#清空yum缓存

yum clean all

#重建yum缓存

yum makecache

#列出yum列表

yum list