此处都以阿里云的镜像为例子；Ubuntu分为ARM版本和x86版本

阿里云镜像网站：https://opsx.alibaba.com/mirror

里面有ubuntu源的设置说明

以ubuntu16.04为例：

x86版本

deb http://mirrors.aliyun.com/ubuntu/ xenial main

deb-src http://mirrors.aliyun.com/ubuntu/ xenial main

deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main

deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main

deb http://mirrors.aliyun.com/ubuntu/ xenial universe

deb-src http://mirrors.aliyun.com/ubuntu/ xenial universe

deb http://mirrors.aliyun.com/ubuntu/ xenial-updates universe

deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates universe

deb http://mirrors.aliyun.com/ubuntu/ xenial-security main

deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main

deb http://mirrors.aliyun.com/ubuntu/ xenial-security universe

deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security universe

ARM版本

deb http://mirrors.aliyun.com/ubuntu-ports/ xenial main

deb-src http://mirrors.aliyun.com/ubuntu-ports/ xenial main

deb http://mirrors.aliyun.com/ubuntu-ports/ xenial-updates main

deb-src http://mirrors.aliyun.com/ubuntu-ports/ xenial-updates main

deb http://mirrors.aliyun.com/ubuntu-ports/ xenial universe

deb-src http://mirrors.aliyun.com/ubuntu-ports/ xenial universe

deb http://mirrors.aliyun.com/ubuntu-ports/ xenial-updates universe

deb-src http://mirrors.aliyun.com/ubuntu-ports/ xenial-updates universe

deb http://mirrors.aliyun.com/ubuntu-ports/ xenial-security main

deb-src http://mirrors.aliyun.com/ubuntu-ports/ xenial-security main

deb http://mirrors.aliyun.com/ubuntu-ports/ xenial-security universe

deb-src http://mirrors.aliyun.com/ubuntu-ports/ xenial-security universe

你也可以同样的方法去改其它的镜像网站的源。

修改源之后执行

apt-get update

apt-get upgrade

搞之前，别忘了把自带的源给备份一下，稳妥一点嘛！