The utility model relates to a train accuracy positioning system based on synthesize location, including big dipper satellite system, still include terrestrial system and on -vehicle system, the terrestrial system is including the location based service center and a plurality of difference basic stations that are used for providing satellite positioning difference information for the train that are used for providing train circuit cartographic information, and on -vehicle system is including the positioning antenna, positioner and the vehicular computer that connect gradually, and positioning antenna is connected with location based service center, difference basic station and big dipper satellite system respectively, and location based service all is connected with big dipper satellite system central and difference basic station, positioner passes through positioning antenna and receives big dipper satellite system's the satellite signal and the difference information of difference basic station, carries out obtaining after the resolving of satellite positioning train position data and erupts simultaneously and give vehicular computer. Compared with the prior art, the utility model has the advantages of the location is accurate.