The invention relates to a precise train positioning system based on comprehensive positioning. The precise train positioning system comprises a beidou satellite system, and further comprises a ground system and a vehicle-mounted system, wherein the ground system comprises a positioning service center for providing train route map information and a plurality of differential base stations for providing satellite positioning differential information for a train; the vehicle-mounted system comprises a positioning antenna, a positioning device and a vehicle-mounted computer which are connected in sequence; the positioning antenna is connected with the positioning service center, the differential base stations and the beidou satellite system; the positioning service center and the differential base stations are connected with the beidou satellite system; the positioning device receives a satellite signal of the beidou satellite system and differential information of the differential base stations, performs satellite positioning calculation to obtain train position data and sends the train position data to the vehicle-mounted computer. Compared with the prior art, the precise train positioning system disclosed by the invention has the advantages of precise positioning and the like.