Hi,My parents inlaw are Pakistani national and also permanent residents of Saudi Arabia.

If their son has residence permit in China, they can apply for S2 type for China which may allow them to stay for not more than 6 months in China.
The required documents include their residence permit in Saudi Arabia, passport and its copy, the fully filled-out application form, a passport-style photo, an invitation letter from their son and copies of his residence permit and passport, as well as the relations ship certificate. Usually, the university doesn’t need to provide any documents.