paper band filter is mainly composed of fluid tank, dirty paper box, filter non-woven (generally called paper), driving mechanism, signaler mechanism, speed reducer and liquid pump etc. During operation, the chain and silk screen of the transmission mechanism are at the state of cambered surface; the non-woven covering on they are cambered. Hence, when the soiling solution containing impurities are poured on the non-woven, thin chips and impurities are absorbed on the non-woven. With the increase of dirt on the non-woven, the non-woven will be blocked; the level of dirty fluid will rise; the liquid level controller will float; the signaler mechanism will give a signal; the speed reducer drives chain and silk screen to move; dirt and dirty cloth drop into the dirty paper box, so as to realize automatic replace of filter cloth. After the filter cloth is replaced, the descending machine of fluid level stops operation and enters the next work filter circulation. The purified fluid in the fluid tank will be transferred to the main unit by the liquid pump.