sudo nano /etc/ntp.conf
然后找到
# pool.ntp.org maps to about 1000 low-stratum NTP servers. Your server will
# pick a different set every time it starts up. Please consider joining the
# pool: <http://www.pool.ntp.org/join.html>
server 0.debain.pool.ntp.org iburst
server 1.debain.pool.ntp.org iburst
server 2.debain.pool.ntp.org iburst
server 3.debain.pool.ntp.org iburst
或者类似的东西，把它改成
# pool.ntp.org maps to about 1000 low-stratum NTP servers. Your server will
# pick a different set every time it starts up. Please consider joining the
# pool: <http://www.pool.ntp.org/join.html>
server asia.pool.ntp.org iburst
重启即可
原理： 原来的NTP服务器pool（提供服务器名称的网站）貌似被墙了，因此改成这样（asia.pool.ntp.org）
解决 RaspberryPi 树莓派 NTP服务异常 无法自动同步时间
原文：http://www.cnblogs.com/turtlegood/p/4906643.html