The invention relates to the technical field of heating and ventilation pipe cleaning, in particular to a water scale clearing device for a heating and ventilation pipe. The water scale clearing device for the heating and ventilation pipe aims at achieving the technical effects that an antiscaling agent can be in full contact with water scale in the heating and ventilation pipe, and meanwhile, theheating and ventilation pipe can be flushed. The water scale clearing device for the heating and ventilation pipe comprises a first mounting plate, a collection frame, a first one-way valve, a driving mechanism, a liquid outlet mechanism, a cleaning mechanism, a liquid inlet pipe, a fifth mounting plate, universal wheels, a storage frame and the like. A cover plate is hinged to the top f the storage frame. The collection frame is put at the top of the fifth mounting plate. The first mounting plate is fixedly connected to the top of the fifth mounting plate in the vertical direction. The liquid outlet mechanism is fixedly connected to the top of a second mounting plate. The driving mechanism is fixedly connected to the side of the storage frame. By means of the water scale clearing device,the antiscaling agent can be conveniently and rapidly delivered to the inner side wall of the heating and ventilation pipe for scale removal, and thus, the effect that the scale removal speed is increased is achieved.