The invention relates to an unloading device of a railway freight transportation hopper car. The unloading device is a link mechanism arranged between a pneumatic unloading device and a hand-operatedunloading device of the railway freight transportation hopper car, belonging to the rail traffic field. The unloading device comprises a clutch and a main air pipe of a pneumatic system, wherein the clutch is arranged on a poking fork which has a poking pin; the poking fork is arranged on a main transmission shaft which is arranged on a support; and the main transmission shaft is provided with a handle. The key technology of the unloading device comprises the following steps that: the handle is connected with a connecting rod, and the other end of the connecting rod is connected with a changeover cock which is arranged on the main air pipe of the pneumatic system. The unloading device adopts a linkage mechanism, that is, the handle, the connecting rod, the changeover cock and the car bodyare formed into a four-linkage mechanism; therefore, by means of the transmission function of the four-linkage mechanism and the switching of the changeover cock, hand-operated action is realized whenpneumatic function is shut down, thereby solving the problem of pneumatic misoperation during hand-operated unloading. In addition, the linkage mechanism can reach the goal of reliable operation through controlling the length and the position of the connecting rod so as to eliminate hidden danger.