China Nationality Holder living in Singapore departing to Hong Kong. Do i require a visa for a 5D4N?

Sara, after your stay in HK, where will you go? If you plan to go to mainland or a third country, you don't need the HK entry permit. If you want to go back to Singapore, you should apply for an entry permit. The processing takes four working days and costs 15 Singaporean dollars. You can entrust an agent to submit the apploication for you.