how do i purchase train ticket in china?

Thanks for the widely used information technology in China, now you are much easier to purchase a train ticket in a railway station in China. Why? Because most Chinese people can purchase their ticket using mobile apps or on the Internet, and then claim their tickets in railway station automatic machines by scanning their Chinese IDs. 

As a foreigner in China, do you have to go to the railway station to purchase an airplane ticket?

Based on my experience in Beijing, the answer is NO! I purchased four train tickets online https://www.trip.com, Choose language as English, you can type English to see all the available tickets from your city to the destination city. And you can pay the fare using your credit card! And the best thing, you do not need to go to the railway station, line up, and purchase a ticket(s). 

Although I had an unfortunate incident that I purchased wrong date train tickets and wasted lots of money (this may be an advantage to purchasing your tickets in the railway station, you will not buy wrong date train tickets because the ticket person knows precisely what days today and tomorrow are!), I still like the idea of buying tickets online and then go to the ticket claim window to get real train tickets. 

Hope this helps you in purchasing train tickets in China! Right now I am on a train from Beijing to Shanghai, and I did notice there are tens of thousands of trees planted in suburban Beijing to help improve the environment of Beijing. Awesome!