Your son can apply for Chinese visa through China embassy or consulate in Canada, he should prepare the following 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. copy of legal entry permit to Canada or valid Canadian visa.