Booking an original train is easier than booking a passing-by train. You can book a train ticket 60 days in advance at most. So you can decide when to buy the ticket according to your situation. The website that our Chinese people mostly used is
http://www.12306.cn/mormhweb/.

Here is some tips for you to take the train: You need to take the luggages by yourself and keep an eye of them on transporting time, no luggage-checking service on the train. It may be crowded when in the domestic travel seasons as well as summer holidays.