The paper tape filter relies on the gravity filter cloth of the liquid itself to isolate the debris, so as to achieve the purpose of purifying the liquid body. The chain and mesh of the transmission mechanism form a certain depth of the liquid pool, and the filter cloth is spread on the chain and the mesh. When the dirty liquid carrying impurities flows to the non-woven fabric through the water buffer device, the impurities are separated by the filter cloth to form a filter cake, the filter cake is getting thicker and thicker, the dirty liquid level rises, the floating level controller sends a signal, the reducer starts, and drags the filter cloth, dirt and dirty cloth into the dirty carton, so as to realize the automatic replacement of the filter cloth; After the filter cloth is updated, the liquid level of the dirty liquid drops, the reducer stops rotating, and the machine enters the next filtration cycle. The filtered pure liquid is transported to the main engine by the liquid pump.