Originally Posted by
seawolf
If you are departing US for China, show check-in agent in US both passports. You've done your part in complying with US requirement to depart on US passport. In the unlikely event CBP raise a stink you didn't use your US passport to depart, the fault is with the airline as you presented both passports.
Show DE passport to Chinese immigration
Returning to US from China, show check-in agent in China US passport (and DE if asked).
Show DE passport to Chinese immigration
Show US passport to CBP
Yup.
Showing multiple passports is fine so long as it is legal to possess them (if you were a China/US and showed both your Chinese one would be immediately cancelled as China doesn't permit dual citizenship), although you'll get a few clueless checkin people. (Hey, before you say I don't have a visa, why don't you notice the second passport rubber-banded to the one you're looking at?? You think I did that as a joke?)