yes, you have to apply for a China tourist visa to visit your parent-in-law in China, you need to prepare the below documents:
1. One completely filled out visa application form. No item should be blank .

2. One recently taken 2X2 inch photo showing entire face and without a hat on. Please affix the photo to the application form.

3. Original passport with at least 2 blank visa pages and valid for at least 6 months beyond the date of application.

4. Round trip airline ticket and hotel reservation. Application for visiting family or friends should provide certificate of relationship.

5. SPR