According to the immigration laws of Hong Kong, foreign students have to obtain a student visa before coming to Hong Kong, unless you have a permanent Hong Kong Identity (HKID) card. And you have to possess a valid student visa during your stay in Hong Kong.

If you are staying in Hong Kong for more than 180 days, you are encouraged to apply for a Hong Kong Identity Card (HKID). With an HKID Card, you are able to stay in the general ward and to receive medical treatment at a subsidized rate of HK$ 100 per day with an admission fee of HK$ 50 (current exchange rate).