The oil filter element is mainly used for the filtration of oil in the hydraulic system and is installed in the filter and oil filter in the hydraulic system. In the oil circuit of the hydraulic system, it is used to remove the metal powder and other mechanical impurities worn by the components in the hydraulic system to keep the oil circuit clean and prolong the life of the hydraulic system; the low-pressure series filter element has no bypass valve. When the filter element is not replaced in time, the bypass valve can be automatically opened to ensure the normal operation of the system.