Bridging device for railway flat car

A bridging device for a railway flat car comprises a chassis car (1) with driving performance and an erecting device (4) with a hoisting lazy arm (41), a secondary frame assembly (3) being arranged on the chassis car (1) and providing a moving guide rail for the erecting device (4), and a platform plate assembly (2) connected with the hoisting lazy arm (41) of the erecting device (4) and used for being in lap joint with the railway flat car. The platform plate assembly (2) is in lap joint between the railway flat car and the ground by the secondary frame assembly (3) and the erecting device (4), a platform plate does not need to be erected and the transfer efficiency of large-sized machinery and equipment on the railway flat car is improved.