forget 中國戶口

better get your kid back here now before 旅行證expires. just take 旅行證-with China border Entry stamp on it to show that he entered the country legally--, and his US passport--that he is a U.S. citizen-- so that China's border control will let him out. do not show his 中國戶口to china border control. with US passport he should be allowed to enter US easily when passing thru border control here in the U.S. also, better get his birth certificate with him too.

people think it's very easy to send kids to china but if you do plan to let them stay there for a while, better investigate, not just go by your own imagination.

10 yrs ago, entry/exit card was still required and our kid over-stayed one year there. so we had to deal with local police dept to get his exit card re-issued, a lot of headache.