Automatic differential pressure filter using foreign technology, according to the principles of fluid mechanics, hydraulic drive theory and mechatronics control methods, combined with domestic water quality requirements of the development of efficient water treatment equipment. 
 When the differential pressure liquid containing the solid phase through the inlet into the filter, the filtration process continues, the liquid within the solid phase impurities trapped in the filter element surface, causing increased pressure, the filtration resistance increased, decreased filtration efficiency. 
 When the solid phase impurities are retained to a certain extent, so that the filter elements on both sides of the differential pressure reaches the set value, the differential pressure controller provides the signal to the control cabinet, control cabinet to receive the signal to the electric valve, electric valve automatically open, hydraulic or electromechanical with the outfall the sewage and sewage after a period of time-sensitive, motorized valve automatically shuts the valve, when the pressure difference on both sides of the filter element reaches the set value, repeat the above operation, to filter effects.