1：yum install yum-priorities ：安装优先级插件
2：rpm -Uvh http://mirrors.ustc.edu.cn/fedora/epel/6/x86_64/epel-release-6-8.noarch.rpm： 安装epel源文件，请注意这是64位的
3：修改该文件，不然会出现错误：
Error: Cannot retrieve metalink for repository: epel. Please verify its path and try again
vim /etc/yum.repos.d/epel.repo，修改如下：
baseurl=http://download.fedoraproject.org/pub/epel/6/$basearch/debug
#mirrorlist=
https://mirrors.fedoraproject.org/metalink?repo=epel-debug-6&arch=$basearch
第二种方法（centos7也适用）：
然后执行yum clean all
yum makecache即可
centos7的epel源
编辑/etc/yum.repos.d/epel.repo
[epel] name=Extra Packages for Enterprise Linux 7 - $basearch #baseurl=http://download.fedoraproject.org/pub/epel/7/$basearch mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-7&arch=$basearch failovermethod=priority enabled=1 gpgcheck=0 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7 [epel-debuginfo] name=Extra Packages for Enterprise Linux 7 - $basearch - Debug #baseurl=http://download.fedoraproject.org/pub/epel/7/$basearch/debug mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-debug-7&arch=$basearch failovermethod=priority enabled=0 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7 gpgcheck=1 [epel-source] name=Extra Packages for Enterprise Linux 7 - $basearch - Source #baseurl=http://download.fedoraproject.org/pub/epel/7/SRPMS mirrorlist=https://mirrors.fedoraproject.org/metalink?repo=epel-source-7&arch=$basearch failovermethod=priority enabled=0 gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-EPEL-7 gpgcheck=1 |
4：yum repolist：检查是否添加到源列表,如出现以下文字则添加成功：
repo id repo name status
base CentOS-6 - Base 6,575
epel Extra Packages for Enterprise Linux 6 - x86_64 11,886
extras CentOS-6 - Extras 45
updates CentOS-6 - Updates 671
repolist: 19,177