参考官方文档：
https://www.virtualbox.org/wiki/Linux_Downloads
配置yum源：
vim /etc/yum.repos.d/virtualbox.repo
[virtualbox]
name=Oracle Linux / RHEL / CentOS-$releasever / $basearch - VirtualBox
baseurl=http://download.virtualbox.org/virtualbox/rpm/el/$releasever/$basearch
enabled=
gpgcheck=
repo_gpgcheck=
gpgkey=https://www.virtualbox.org/download/oracle_vbox.asc
然后用yum直接安装即可：
yum install VirtualBox-5.1