hello, family visa application

Your wife can apply for student X type, you and your son can apply for S type for mainland China. First, prepare the relevant documents including passport and its copy, the application form, passport-style photo, admission letter and JW form from the school as schooling certificate of your wife, and your marriage certificate and your son's birth certificate and others. Next, submit the application to the China embassy.

thank you Peterson,
your answer is very helpful. I was browsing some websites, they said S application needs resident permit of student or worker who invites the family members.
is It possible that we apply S without her resident permit?

You can have a try. But the result cannot be guaranteed. Good luck.