1) 备份原来的源 cp /etc/apt/source.list /etc/apt/source.list.old
2) 用下面的文件覆盖 /etc/apt/source.list
# 163（非教育网推荐）
deb http://mirrors.163.com/ubuntu/ precise main restricted
deb-src http://mirrors.163.com/ubuntu/ precise main restricted
deb http://mirrors.163.com/ubuntu/ precise-updates main restricted
deb-src http://mirrors.163.com/ubuntu/ precise-updates main restricted
deb http://mirrors.163.com/ubuntu/ precise universe
deb-src http://mirrors.163.com/ubuntu/ precise universe
deb http://mirrors.163.com/ubuntu/ precise-updates universe
deb-src http://mirrors.163.com/ubuntu/ precise-updates universe
deb http://mirrors.163.com/ubuntu/ precise multiverse
deb-src http://mirrors.163.com/ubuntu/ precise multiverse
deb http://mirrors.163.com/ubuntu/ precise-updates multiverse
deb-src http://mirrors.163.com/ubuntu/ precise-updates multiverse
deb http://mirrors.163.com/ubuntu/ precise-backports main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ precise-backports main restricted universe multiverse
deb http://mirrors.163.com/ubuntu/ precise-security main restricted
deb-src http://mirrors.163.com/ubuntu/ precise-security main restricted
deb http://mirrors.163.com/ubuntu/ precise-security universe
deb-src http://mirrors.163.com/ubuntu/ precise-security universe
deb http://mirrors.163.com/ubuntu/ precise-security multiverse
deb-src http://mirrors.163.com/ubuntu/ precise-security multiverse
deb http://extras.ubuntu.com/ubuntu precise main
deb-src http://extras.ubuntu.com/ubuntu precise main
# sohu（非教育网推荐）
deb http://mirrors.sohu.com/ubuntu/ precise main restricted
deb-src http://mirrors.sohu.com/ubuntu/ precise main restricted
deb http://mirrors.sohu.com/ubuntu/ precise-updates main restricted
deb-src http://mirrors.sohu.com/ubuntu/ precise-updates main restricted
deb http://mirrors.sohu.com/ubuntu/ precise universe
deb-src http://mirrors.sohu.com/ubuntu/ precise universe
deb http://mirrors.sohu.com/ubuntu/ precise-updates universe
deb-src http://mirrors.sohu.com/ubuntu/ precise-updates universe
deb http://mirrors.sohu.com/ubuntu/ precise multiverse
deb-src http://mirrors.sohu.com/ubuntu/ precise multiverse
deb http://mirrors.sohu.com/ubuntu/ precise-updates multiverse
deb-src http://mirrors.sohu.com/ubuntu/ precise-updates multiverse
deb http://mirrors.sohu.com/ubuntu/ precise-backports main restricted universe multiverse
deb-src http://mirrors.sohu.com/ubuntu/ precise-backports main restricted universe multiverse
deb http://mirrors.sohu.com/ubuntu/ precise-security main restricted
deb-src http://mirrors.sohu.com/ubuntu/ precise-security main restricted
deb http://mirrors.sohu.com/ubuntu/ precise-security universe
deb-src http://mirrors.sohu.com/ubuntu/ precise-security universe
deb http://mirrors.sohu.com/ubuntu/ precise-security multiverse
deb-src http://mirrors.sohu.com/ubuntu/ precise-security multiverse
deb http://extras.ubuntu.com/ubuntu precise main
deb-src http://extras.ubuntu.com/ubuntu precise main
保存后 执行
apt-get update 即可