Abstract: With the increasing of large GPS networks,The request to rapidly process the synchronous mass GPS data is more and more urgently.In this paper,a rapid algorithm,which is based on zero-difference precise point position(PPP) techniques and more suitable to process large GPS networks—Ambizap,is introduced,its characteristic and realization are studied.The algorithm performance on a test network including 150 GPS stations shows that the precision of Ambizap solution is more higher than that of PPP solution,and the efficiency of Ambizap is more higher than that of multi-baseline method.Ambizap method is of practical value for high precision and large GPS networks.