Foreign is ok. I just did it. For the payment site, Alipay (which is the only option to pay), I downloaded the Alipay app English version and took a picture of my US passport to complete the verification/security process. For the ticketing site, damai.cn, I used a Hong Kong phone number to register (I don't know if a foreign phone number would work or not). After I chose my seat, I was asked to put in my ID information and in this case, my passport was the eligible form.Do you need a Chinese passport or can you use a foreign one?