回复：关 于 H1B 回 国 签 证 问 题

You need apply H1B visa in China.

Everyone has to turn in I-94 to leave USA.

you need:
1) I-794 Form
2) Sometimes required the copies of the petition form for I-794
3) Better carry a proof letter from your boss.
4) Financial aid (payroll, bank statement, etc.)

I changed my status from F1 to H1B, since then, I travel between China and USA many times, no problem at all.