if she goes back to china

She can hire an attorney to file in the US court, you have to pay child support by US court, which is pretty bad. Because her income would be low compare to your income, not to mention in china, she has grey income she could hide.

I do not think the court in China can force you to pay child support.

If you love your son, no matter how much child support you pay, you will alwayd his father, he would always miss you. Think about Obma. Of course, if his mom always teach him to hate you, it would be another case. Anyway, children from divorced family would have a tough life in China than in usa.