Both my husband and myself are naturalized citizens of U.S.A. We are both born in Hong Kong. Our son is born in the U.S. He lived in Hong Kong during his early childhood and hold a Hong Kong 3-star Hong Kong ID. This September, he is going to China to study. However, prior to school starts, he wants to do an internship (no pay) with a company in China. What kind of visa does he need for his internship prior to school? During school year, can he work as a student, for pay or no pay?? Would that violate his student visa?

Thank you for your help.