Abstract: In order to restrict the models error of fitting gravimetric quasi-geoid to GPS/leveling quasi-geoid,the new method of fitting two kind quasi-geoid using Bayesian regulation BP neural network was proposed.Using the gravimetric quasi-geoid and GPS/leveling data in a certain area,the new method was compared with polynomial surface fitting method.In the case with biggish area and anomalous difference between two kind of quasi-geoid,Bayesian regulation BP neural network could reduce the erros of models,and Bayesian regulation arithmetic could improve the structure of network by restricting weights to produce a smoother network response.The experimental result shows that the new method can improve the inner and outer precisions of fitting two kinds of quasi-geoid clearly.