把CentOS-Base.repo里面的

mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra

这个属性注释掉

baseurl=https://mirrorlist.centos.org/centos/$releasever/os/$basearch/

$releasever这个一定要改系统对应版本

https://mirrors.aliyun.com/centos-vault/  这个换成国内的源

阿里云开源镜像站资源目录

清华大学开源软件镜像站 | Tsinghua Open Source Mirror

我的centos是6.6 改

baseurl=https://mirrors.aliyun.com/centos-vault/6.6/updates/$basearch/

改好

# 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-$releasever - Base
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os&infra=$infra
#baseurl=https://mirrorlist.centos.org/centos/$releasever/os/$basearch/
baseurl=https://mirrors.aliyun.com/centos-vault/6.6/os/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#released updates 
[updates]
name=CentOS-$releasever - Updates
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates&infra=$infra
#baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/$releasever/updates/$basearch/
baseurl=https://mirrors.aliyun.com/centos-vault/6.6/updates/$basearch/
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras&infra=$infra
#baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/$releasever/extras/$basearch/
baseurl=https://mirrors.aliyun.com/centos-vault/6.6/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-$releasever - Plus
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus&infra=$infra
#baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/$releasever/centosplus/$basearch/
baseurl=https://mirrors.aliyun.com/centos-vault/6.6/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-$releasever - Contrib
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib&infra=$infra
#baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos-vault/$releasever/contrib/$basearch/
baseurl=https://mirrors.aliyun.com/centos-vault/6.6/contrib/$basearch/
gpgcheck=1
enabled=0
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6

成新的缓存

 yum makecache