centos7系统库中默认是没有Nginx的rpm包的，所以我们自己需要先更新下rpm依赖库

(1)使用yum安装Nginx需要包括Nginx的库，安装Nginx的库

#rpm -Uvh http://Nginx.org/packages/centos/7/noarch/RPMS/Nginx-release-centos-7-0.el7.ngx.noarch.rpm

(2)使用下面命令安装Nginx

#yum install Nginx

(3)启动Nginx

#service Nginx start

或

#systemctl start Nginx.service

本文转自：http://www.cnblogs.com/Robert-huge/p/6003934.html