If the next job is still in China, you will probably need a release letter from the company. They "own" any converted license, and could make it difficult for you to try and transfer to a different company. The No Incident or Accident letter normally comes from the company. The company may also have a stamp or seal that you could get over a logbook entry, stating something to the effect that the logged hours are true and correct (The stamp or seal that is used on the company documents should be appropriate for the logbook). The no criminal record shouldn't be an issue to get from a local station, just make sure you do it early. Don't be surprised though if a different Chinese company requires a police record from home, not wherever you were in China.....it has happened.
If not for another position in China, the logbook entry and stamp, plus No Inc./Acc. letter, and police record would probably be enough. Depending on how you are leaving the company, anything but the police record could be an issue to get.
Getting tired of China already?