I've done lots of travelling on Chinese trains and would say that once you've made it to the station it's quite difficult to miss your train, or catch the wrong one. The key is the train number. There are always boards which display the train number, and he can always get directions from any staff member (show your ticket and they'll point where to go). Tickets are checked at the door to the carriage and it's always good to state your destination and get confirmation.

Assuming that your father isn't totally clueless he should have no problems.