Diplomats on Wednesday said Pakistan and Algeria have also opposed the new draft while Russia and Brazil have raised some objections.
"It would be difficult for us to support it as it would for a number of other delegations," China's UN ambassador Wang Guangya said.
The US wants a vote on the resolution by Friday. It needs a minimum of nine votes in favour and no vetoes to pass.
A "no" vote from a permanent member – China, Russia, Britain, France or the US - is tantamount to a veto.
"It would be difficult for us to support it as it would for a number of other delegations"
China's UN ambassador
The revised draft put forward by the US empowers the UN to "contemplate" oil sanctions, instead of "will order sanctions" as suggested in an earlier draft.
Sudan began exporting oil in 1999 and China is a key buyer.
Pakistani ambassador Munir Akram said he opposed the sanctions threat and a ban on Khartoum's military planes flying over Darfur.
"We think it is premature at best," he said. "Let's not have empty threats or threats that would make a lot of people die".
Russia's ambassador Andrei Denisov said Moscow had not made a final decision, but they "don't like" the draft.
Sudan has rejected the revised draft.
UN officials estimate that the 19-month conflict in Darfur has claimed 50,000 lives and left 1.4 million people homeless.