The invention provides a dust blocking box. The dust blocking box comprises a blocking box body and a plurality of blocking structures. The blocking box body is a sealed box body, contains water and comprises a top plate and two opposite side plates. The two side plates are both connected with the top plate. A smoke discharging pipe is installed outside one side plate, and a suction structure is installed outside the other side plate. The blocking structures are installed in the blocking box body in sequence. Each blocking structure comprises a lower blocking plate and an upper blocking plate. The bottoms of the lower blocking plates abut against water in the blocking box body. The tops of the upper blocking plates are connected with the top plate. The connection line sequentially connected with central points of the lower blocking plates and central points of the upper blocking plates is in a sawtooth shape. The lower blocking plates are parallel to the upper blocking plates. The bottom of each lower blocking plate and the bottom of each upper blocking plate both incline towards the smoke discharging pipe. The suction structure is used for sucking smoke in the smoke discharging pipe into the blocking box body, and the smoke is sucked out through the suction structure after sequentially passing through the lower blocking plates and the upper blocking plates.