The utility model relates to a positioning device of a rail transportation vehicle. The positioning device comprises laser displacement sensors, a rail vehicle walking distance detection unit and a synchronous acquisition and data processing unit, wherein the laser displacement sensors and the rail vehicle walking distance detection unit are connected with the synchronous acquisition and data processing unit respectively. In the positioning device, the distance between the vehicle and a rail is detected by the vehicle-mounted laser displacement sensors, the walking distance of the vehicle is obtained through outputs of a wheel axle pulse sensor or the two vehicle-mounted laser displacement sensors, and rail characteristic data are obtained by a vehicle-mounted data acquiring and processing module. Acquired rail characteristic data are matched with history data of rail characteristics, so that high-accuracy absolute or relative positioning is realized.