1.What's the benefit for your child if your ex lost his parental right?
2. How can you enforce any US family court order in China? As far as I know, there is no treaty between us and china to enforce such court order.
3. What do you really want from this action? Force your ex to pay child support or force your ex to visit your child? Do you really need his child support money?
4. the most important one: what is best for your child? will take away your ex's parental right benefit your child at all?
Hug again...those are not easy questions. But, life comes with tough questions and choices. Put your child's best interest before your emotion.