Could you try to take the GMAT? Your GRE is indeed a bit low given averages for top 50 schools in the U.S. The GRE and GMAT are very different tests and seem to favor different learning styles / test taking abilities. Especially if you have formal training in finance and economics, you may very well perform better on the GMAT the the GRE since the GRE doesn't reward any experience in these areas. Given that most MBA-hopefuls take the GMAT, I'm sort of curious why you took the GRE in the first place? Were you also looking to apply to other masters programs and wanted to take a test that would be accepted by business schools and masters programs? I'd shoot to raise your test score (with either the GMAT or the GRE)... I have a hunch you can given your previous academic accomplishments (undergrad, masters and PhD from good Chinese university in quant fields... you MUST be smart!!).
However, if you try diligently to raise your GRE or GMAT score and are unable to (unlikely) there ARE some schools that are better-ranked than their test score averages apply such as Babson, University of South Florida, George Washington University, and Rutgers. In general, you should be at or above the average test score of a school in order to have a decent shot with your application.