How do I get an invitation letter?

You can ask for an invitation letter from your son, with copies of his passport and Chinese residence permit. The letter should contain:
(1) Information on the applicant (full name, gender, date of birth, etc.)

(2) Information on the planned visit (arrival and departure dates, place(s) to be visited, etc.)

(3) Information on the inviting individual (name, contact telephone number, address, official stamp, signature of the legal representative or the inviting individual)