I am Congolese and accepted to study in China and want to know the student Visa requirements. And if it is also possible that I can process it in Zambia since it is the nearest.

Rachel, those documents are needed for student X type: your passport and copy of its data page, a completed application form affixed with a passport-style photo, the admission letter from the school and JW form.
If you can provide valid entry permit for Zambia, you can probably apply for it from there.