切换到/etc/yum.repos.d/目录下cd /etc/yum.repos.d

(推荐)备份原有yum源文件mv /etc/yum.repos.d/CentOS-Base.repo /etc/yum.repos.d/CentOS-Base.repo.bak

下载阿里云yum源wget -O /etc//yum.repos.d/CentOS-Base.repo http://mirrors.aliyun.com/repo CentOS-7.repo(以Centos7为例)

清理yum缓存yum clean all

生成新的yum缓存yum makecache