Hi, looking to travel to Nanjing for about 5 days, Im from Singapore, do i need a VISA?

If you go back Singapore after you visit Nanjing, then you need to apply for a visa.

Hi sorry based on this:

Ordinary passport holders of Singapore, Brunei and Japan are allowed to enter China without visas for up to 15 days for tourism, visiting family or friends, or minor business purposes provided they enter through international ports open to foreigners. According to Mutual Visa Exemption, Qatar citizens with ordinary passports may stay in China for less than 30 days without visa. Armenian citizens who stay in China for no more than 90 days every 180 days are exempt from visas.

For nationals of these countries, a visa is required under following circumstance:
(1) Ordinary passport holder visits for tourism, business, visiting friends and relatives but stays for more than 15 days (30 days for Qataris, 90 days for Armenians).
(2) Ordinary passport holder visits for the purposes of study, work, official visit, settling down and interview.
(3) Japanese Diplomatic and Official passport holder.

So is there still a need for VISA?

Well, you are eligible for 15-day visa free policy.