下面提供了 阿里和 清华大学 两个镜像仓库配置操作说明，实际使用时，选择其中一个配置即可，推荐使用清华大学的
1、配置 清华大学镜像仓库（推荐）
地址： https://mirrors.cnnic.cn/ 你可以打开进去看看
（1）、首先备份 CentOS-Base.repo
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak（2）、之后启用 TUNA 软件仓库， 将清华大学镜像仓库信息写入 /etc/yum.repos.d/CentOS-Base.repo
vim /etc/yum.repos.d/CentOS-Base.repo将 CentOS-Base.repo 中的内容 更新为 下面的内容：
# 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-$releasever - Base
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/os/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
#released updates
[updates]
name=CentOS-$releasever - Updates
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/updates/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/extras/$basearch/
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-7
#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
baseurl=https://mirrors.tuna.tsinghua.edu.cn/centos/$releasever/centosplus/$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-7（3）、清除缓存
yum clean all # 清除系统所有的yum缓存
yum makecache # 生成yum缓存2、配置 阿里镜像仓库
进入阿里镜像仓库网站 https://opsx.alibaba.com/mirror/
根据官网的说明，我们详细说说每步骤的意思。
（1）、备份：将 CentOS-Base.repo 为CentOS-Base.repo.backup
mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.backup（2）、下载新的 http://mirrors.aliyun.com/repo/Centos-7.repo,并命名为CentOS-Base.repo
wget -O /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo
或者
curl -o /etc/yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo/Centos-7.repo（3）、清除缓存
yum clean all # 清除系统所有的yum缓存
yum makecache # 生成yum缓存