i plan to visit my son who resides temporialy in china, for two weeks, do i just need tourist visa

If your son is working there, you can apply for a S2 type for a short visit, providing an invitation letter from your son and copies of his passport and residence permit, his birth certificate is also required.

Save the hassle, go for L. Provide your two ways of flight tickets and hotel booking. If you are staying with your son at his rented apartment in China, provide the copy of his passport page, valid resident permit that he's holding and invitation letter from him.