Greetings.
Two questions for you to answer:
1. Why would you want to leave China?
2. Since you fly the 737-300, can you upgrade to another aircraft (if your airline uses other airplanes) or do you have to stay in the 737-300 (can you bid another aircraft type)?
As for your questions, yes, you would need to take a series of tests for European flying. However, if you were to pass and if you were eligible for living and working in the EU, then your 737-300 experience could be very valuable. However, there are many pilots who are unemployed (Sabena, Aero Lloyd), and the competition for pilot positions is very strong at the moment. I would probably stay in China and gain flight experience for the short-term (maybe fly for Cathay or Emirates later).
Good Luck