I understand that you are unable to use your iPhone that you bought from Verizon while in China. I know it's important to have your iPhone working wherever you are, so I'm happy to help.
Since you bought the iPhone from Verizon, I would first recommend contacting them to ensure that it is unlocked:
How to unlock your iPhone - Apple Support
If the iPhone is unlocked and you continue to have issues, then check this article for additional troubleshooting:
If you can't connect to a cellular network or cellular data - Apple Support
Thanks for using the Apple Support Communities. Cheers!