1.打开/etc/apt/sources.list 将内容替换为以下内容（注意把sources.list文件备份一下）
deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
2. 最简单的方法：
打开 sources.list 发现地址都是us.archive.ubuntu.com 这样的地址，将us替换成cn即可
其他源地址：
清华大学开源镜像站：https://mirrors.tuna.tsinghua.edu.cn/help/ubuntu/
网易开源镜像站：http://mirrors.163.com/.help/ubuntu.html
Ubuntu apt install 下载软件很慢的解决办法
原文：https://www.cnblogs.com/jasonboboblog/p/12375555.html