Trains are quite a useful form of transportation in China, especially with the Bullet Trains （动车组）available on routes such as Shanghai to Suzhou that can make the entire distance in only 31 minutes!
You can easily search all of the train schedules online at “train.tielu.org” (铁路).
Note that you can somewhat search in english by typing the “pinyin” name of the city, but it definitely is better to directly type in Chinese. For example, just review the results for searches for “ShanghaiTOSuzhou” vs “上海到苏州“. As always, be careful 😉
There’s also detailed information abut estimated total train size at Gaocan.com