Hi, I am going to go to huangshan via overnight train on the day I arrive .

Yes, you can buy the tickets when you arriving at the train station. But in case the tickets may be sold out, for it is a hot travel route, you are suggested to book train tickets in advance. TravelChinaGuide has online booking service with high efficiency. If interested, the contact information is bookingtravelchinaguide.com. :-)