The event I'm currently attending hosts Ham exams, and it's kind of likely that the student would pass on first attempt; would it make sense for him to take the exam? Can he just go home to China and use the license to transmit on amateur bands?
A bit of Googling led me here: http://www.crac.org.cn/?p=1646
According to that page, a visitor to China would need to submit an application for an "AMATEUR RADIO OPERATOR’S CERTIFICATE FOR VISITORS", along with their foreign licence, their foreign passport and their Chinese visa.
The implication here is that if a Chinese national wants to get a US licence and then operate in China, they can not do that (since they have a Chinese passport and don't have a visa to enter China, obviously).
It sounds like they should take the exam in China to get their local amateur radio licence.
This would depend on what if any reciprocity agreements are in place between the USA and China. If I (a US Amateur Extra license holder) were to travel to Europe as a tourist, I'd need to print a specific document and carry it with me, along with a printed copy of my license (and passport, but I should have that anyway). If I were to travel to most of Latin America, I wouldn't have to do anything special. There are places where I'd have to effectively get a local license (if they'd even issue one to a foreigner) to operate.
One might be able to find out with a call, email, or paper letter to a local Chinese consulate.
The answer to this question is very simple.
Unless a special arrangement has been made, Amateur licenses are generally valid only for operation in the country that the license was issued in.
You can't use a USA issued ham license in China.
As long they have a valid mailing address and are not representing a foreign government they can take the test, and if the pass get a US license and operate in the USA. There is a agreement with China for "visitors" to China to use their US license after approval, but I don't believe that would let a Chinese national or citizen to do so.