The utility model relates to a grain hopper car, concretely speaking, a railway wagon with self-unloading function, belonging to the field of railway transport means. The grain hopper car comprises an underframe and a car body. The underframe includes end sills, body bolsters, cross bearers, draft sills and side sills. The end sills, the body bolsters, the cross bearers, the draft sills and the side sills are arranged at the two ends of the underframe. The side sills are arranged at the two sides of the underframe. The car body includes side wall, end walls and a roof. The bottom of the car body forms a hopper arranged below the underframe. A bottom door is installed on the hopper. A hatch is arranged at the top of the roof. A hatch cover is connected on the hatch. The technical key is that the underframe is a structure without a center sill, large side sills are connected between the draft sills at the two ends of the underframe, and small side sills are respectively arranged at the two ends of the underframe and respectively connected with the large side sills. A transverse beam is installed in an arc support plate. Side wall bracings are respectively installed at the two ends of the transverse beam. End wall bracings and rails are installed on the end plates. The utility model has the advantages that the structure is reasonable, the weight is effectively reduced and the volume is improved.