I want to marry a chinese national, what requirements do I need?

You should get an Affidavit of Single Status to be notarized first by a local Notary Public and then to be authenticated by the Singapore Academy of Law, at last authenticated by the Chinese Embassy in Singapore.

When you make marriage registration, you need to show the Affidavit of Single Status, your valid passport and valid China visa. Singapore ordinary passport holders can stay in China without a China visa for 15 days at most. If you plan to stay in China for less than 15 days, you don't need to apply China visa.