I am a ghanaian by birth and a student in china

Yes, you need it. You can either apply from the HK SAR Office in Beijing or apply by posting documents to the HK Immigration Office. Prepare the following documents: a photocopy of your passport, a photocopy of your residence permit in mainland, an application form, a bare-ehaded photo, a travel itinerary, a financial standing document, and a photocopy of round-trip tickets and hotel reservations.