Now that I have an American visa, can Singapore be visa-free?

With an American visa, transit through Singapore can be exempted for 96 hours. (American visas must be valid for more than one month)

Please note: it's a transit to Singapore, which means that you need to go to other countries later after you arrive in Singapore, so you can avoid the visa for 96 hours. If you go to Singapore, you can't go to other countries or go back to China directly.