1、备份原来的源文件

sudo cp /etc/apt/sources.list /etc/apt/sources.list_backup

2、编辑新源文件

sudo vim /etc/apt/sources.list 

将之前的源全部删除然后加入新源，可选择以下：

#阿里云服务器

# 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

#163

deb http://mirrors.163.com/ubuntu/ trusty main restricted universe multiverse

deb http://mirrors.163.com/ubuntu/ trusty-security main restricted universe multiverse

deb http://mirrors.163.com/ubuntu/ trusty-updates main restricted universe multiverse

deb http://mirrors.163.com/ubuntu/ trusty-proposed main restricted universe multiverse

deb http://mirrors.163.com/ubuntu/ trusty-backports main restricted universe multiverse

deb-src http://mirrors.163.com/ubuntu/ trusty main restricted universe multiverse

deb-src http://mirrors.163.com/ubuntu/ trusty-security main restricted universe multiverse

deb-src http://mirrors.163.com/ubuntu/ trusty-updates main restricted universe multiverse

deb-src http://mirrors.163.com/ubuntu/ trusty-proposed main restricted universe multiverse

deb-src http://mirrors.163.com/ubuntu/ trusty-backports main restricted universe multiverse

#中科大

deb http://debian.ustc.edu.cn/ubuntu/ trusty main multiverse restricted universe

deb http://debian.ustc.edu.cn/ubuntu/ trusty-backports main multiverse restricted universe

deb http://debian.ustc.edu.cn/ubuntu/ trusty-proposed main multiverse restricted universe

deb http://debian.ustc.edu.cn/ubuntu/ trusty-security main multiverse restricted universe

deb http://debian.ustc.edu.cn/ubuntu/ trusty-updates main multiverse restricted universe

deb-src http://debian.ustc.edu.cn/ubuntu/ trusty main multiverse restricted universe

deb-src http://debian.ustc.edu.cn/ubuntu/ trusty-backports main multiverse restricted universe

deb-src http://debian.ustc.edu.cn/ubuntu/ trusty-proposed main multiverse restricted universe

deb-src http://debian.ustc.edu.cn/ubuntu/ trusty-security main multiverse restricted universe

deb-src http://debian.ustc.edu.cn/ubuntu/ trusty-updates main multiverse restricted universe

#sohu

deb http://mirrors.sohu.com/ubuntu/ trusty main restricted universe multiverse

deb http://mirrors.sohu.com/ubuntu/ trusty-security main restricted universe multiverse

deb http://mirrors.sohu.com/ubuntu/ trusty-updates main restricted universe multiverse

deb http://mirrors.sohu.com/ubuntu/ trusty-proposed main restricted universe multiverse

deb http://mirrors.sohu.com/ubuntu/ trusty-backports main restricted universe multiverse

deb-src http://mirrors.sohu.com/ubuntu/ trusty main restricted universe multiverse

deb-src http://mirrors.sohu.com/ubuntu/ trusty-security main restricted universe multiverse

deb-src http://mirrors.sohu.com/ubuntu/ trusty-updates main restricted universe multiverse

deb-src http://mirrors.sohu.com/ubuntu/ trusty-proposed main restricted universe multiverse

deb-src http://mirrors.sohu.com/ubuntu/ trusty-backports main restricted universe multiverse

#oschina

deb http://mirrors.oschina.net/ubuntu/ trusty main restricted universe multiverse

deb http://mirrors.oschina.net/ubuntu/ trusty-backports main restricted universe multiverse

deb http://mirrors.oschina.net/ubuntu/ trusty-proposed main restricted universe multiverse

deb http://mirrors.oschina.net/ubuntu/ trusty-security main restricted universe multiverse

deb http://mirrors.oschina.net/ubuntu/ trusty-updates main restricted universe multiverse

deb-src http://mirrors.oschina.net/ubuntu/ trusty main restricted universe multiverse

deb-src http://mirrors.oschina.net/ubuntu/ trusty-backports main restricted universe multiverse

deb-src http://mirrors.oschina.net/ubuntu/ trusty-proposed main restricted universe multiverse

deb-src http://mirrors.oschina.net/ubuntu/ trusty-security main restricted universe multiverse

deb-src http://mirrors.oschina.net/ubuntu/ trusty-updates main restricted universe multiverse

#北京交通大学

deb http://mirror.bjtu.edu.cn/ubuntu/ trusty main multiverse restricted universe

deb http://mirror.bjtu.edu.cn/ubuntu/ trusty-backports main multiverse restricted universe

deb http://mirror.bjtu.edu.cn/ubuntu/ trusty-proposed main multiverse restricted universe

deb http://mirror.bjtu.edu.cn/ubuntu/ trusty-security main multiverse restricted universe

deb http://mirror.bjtu.edu.cn/ubuntu/ trusty-updates main multiverse restricted universe

deb-src http://mirror.bjtu.edu.cn/ubuntu/ trusty main multiverse restricted universe

deb-src http://mirror.bjtu.edu.cn/ubuntu/ trusty-backports main multiverse restricted universe

deb-src http://mirror.bjtu.edu.cn/ubuntu/ trusty-proposed main multiverse restricted universe

deb-src http://mirror.bjtu.edu.cn/ubuntu/ trusty-security main multiverse restricted universe

deb-src http://mirror.bjtu.edu.cn/ubuntu/ trusty-updates main multiverse

# 北京理工

deb http://mirror.bjtu.edu.cn/ubuntu/ precise main multiverse restricted universe

deb http://mirror.bjtu.edu.cn/ubuntu/ precise-backports main multiverse restricted universe

deb http://mirror.bjtu.edu.cn/ubuntu/ precise-proposed main multiverse restricted universe

deb http://mirror.bjtu.edu.cn/ubuntu/ precise-security main multiverse restricted universe

deb http://mirror.bjtu.edu.cn/ubuntu/ precise-updates main multiverse restricted universe

deb-src http://mirror.bjtu.edu.cn/ubuntu/ precise main multiverse restricted universe

deb-src http://mirror.bjtu.edu.cn/ubuntu/ precise-backports main multiverse restricted universe

deb-src http://mirror.bjtu.edu.cn/ubuntu/ precise-proposed main multiverse restricted universe

deb-src http://mirror.bjtu.edu.cn/ubuntu/ precise-security main multiverse restricted universe

deb-src http://mirror.bjtu.edu.cn/ubuntu/ precise-updates main multiverse restricted universe

restricted universe

#上海交大

deb http://ftp.sjtu.edu.cn/ubuntu/ trusty universe restricted multiverse maindeb http://ftp.sjtu.edu.cn/ubuntu/ trusty-security universe restricted multiverse maindeb http://ftp.sjtu.edu.cn/ubuntu/ trusty-updates universe restricted multiverse maindeb http://ftp.sjtu.edu.cn/ubuntu/ trusty-proposed universe restricted multiverse maindeb http://ftp.sjtu.edu.cn/ubuntu/ trusty-backports universe restricted multiverse main

3、执行 sudo apt-get update

4、执行 sudo apt-get upgrade