lsb_release -a
查看Codename，在后面需要把trusty更换为它.

查看阿里源是否有你的Codename:
http://mirrors.aliyun.com/ubuntu/dists/

添加新的源文件：
sudo vi sources.list

并添加以下内容：注意，每一行的trusty应该用第一步查看得到的Codename来代替

deb http://mirrors.aliyun.com/ubuntu/ trusty main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ trusty-backports main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ trusty-proposed main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ trusty-security main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ trusty-updates main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-backports main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-proposed main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-security main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ trusty-updates main multiverse restricted universe

sudo sed -i.bak s/trusty/Codename/g /etc/apt/source.list`

保存并且执行如下命令，更新成功：
sudo apt-get update

最后附上我用的源：

# 搜狐源
deb http://mirrors.sohu.com/ubuntu/ xenial-updates main restricted
deb-src http://mirrors.sohu.com/ubuntu/ xenial-updates main restricted
deb http://mirrors.sohu.com/ubuntu/ xenial universe
deb-src http://mirrors.sohu.com/ubuntu/ xenial universe
deb http://mirrors.sohu.com/ubuntu/ xenial-updates universe
deb-src http://mirrors.sohu.com/ubuntu/ xenial-updates universe
deb http://mirrors.sohu.com/ubuntu/ xenial multiverse
deb-src http://mirrors.sohu.com/ubuntu/ xenial multiverse
deb http://mirrors.sohu.com/ubuntu/ xenial-updates multiverse
deb-src http://mirrors.sohu.com/ubuntu/ xenial-updates multiverse
deb http://mirrors.sohu.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirrors.sohu.com/ubuntu/ xenial-backports main restricted universe multiverse
# 网易源：
deb http://mirrors.163.com/ubuntu/ xenial-updates main restricted
deb-src http://mirrors.163.com/ubuntu/ xenial-updates main restricted
deb http://mirrors.163.com/ubuntu/ xenial universe
deb-src http://mirrors.163.com/ubuntu/ xenial universe
deb http://mirrors.163.com/ubuntu/ xenial-updates universe
deb-src http://mirrors.163.com/ubuntu/ xenial-updates universe
deb http://mirrors.163.com/ubuntu/ xenial multiverse
deb-src http://mirrors.163.com/ubuntu/ xenial multiverse
deb http://mirrors.163.com/ubuntu/ xenial-updates multiverse
deb-src http://mirrors.163.com/ubuntu/ xenial-updates multiverse
deb http://mirrors.163.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirrors.163.com/ubuntu/ xenial-backports main restricted universe multiverse
# ali源
deb http://mirrors.aliyun.com/ubuntu/ xenial main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-proposed main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-security main multiverse restricted universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-proposed main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main multiverse restricted universe
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main multiverse restricted universe