The application provides a powerful extension bar, comprising a body, a water diversion member, a fixed part, an elastic flexible pipe, a first control part and a movable part. End parts of two ends of the body are provided with a first connection part and a water injection hole communicated with a water inlet hole. The fixed part is fixed on the side wall of the body close to one end of the firstconnection part. The movable part is slidably mounted on the side wall of the body close to one end of a second connection part. The elastic flexible pipe is mounted on the fixed part and the movablepart. A cavity is formed between the elastic flexible pipe and the body. A polishing layer is arranged on the side wall of the elastic flexible pipe away from one side of the body. A first control part is used for controlling a water flow to flow from the water injection hole. The elastic flexible pipe of the present application can accumulate water to expand, thereby achieving sealing of the coal seam drilling; the water diversion member and the first control member simultaneously satisfy the requirements of coal seam water injection and sealing; the polishing layer is used to enable the powerful extension bar to have the function of polishing a coal seam sealing hole.