1.打开终端，进入目录： cd /etc/apt
2.备份一下原来的source文件：sudo cp sources.list sources.list.bak
3.打开source文件，sudo gedit /etc/apt/sources.list
将内容替换为：
# deb cdrom:[Ubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1)]/ xenial main restricted
deb-src http:
//archive.ubuntu.com/ubuntu xenial main restricted #Added by software-properties
deb http:
//mirrors.aliyun.com/ubuntu/ xenial main restricted
deb-src http:
//mirrors.aliyun.com/ubuntu/ xenial main restricted multiverse universe #Added by software-properties
deb http:
//mirrors.aliyun.com/ubuntu/ xenial-updates main restricted
deb-src http:
//mirrors.aliyun.com/ubuntu/ xenial-updates main restricted multiverse universe #Added by software-properties
deb http:
//mirrors.aliyun.com/ubuntu/ xenial universe
deb http:
//mirrors.aliyun.com/ubuntu/ xenial-updates universe
deb http:
//mirrors.aliyun.com/ubuntu/ xenial multiverse
deb http:
//mirrors.aliyun.com/ubuntu/ xenial-updates multiverse
deb http:
//mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http:
//mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse #Added by software-properties
deb http:
//archive.canonical.com/ubuntu xenial partner
deb-src http:
//archive.canonical.com/ubuntu xenial partner
deb http:
//mirrors.aliyun.com/ubuntu/ xenial-security main restricted
deb-src http:
//mirrors.aliyun.com/ubuntu/ xenial-security main restricted multiverse universe #Added by software-properties
deb http:
//mirrors.aliyun.com/ubuntu/ xenial-security universe
deb http:
//mirrors.aliyun.com/ubuntu/ xenial-security multiverse
4.更新：sudo apt-get update