The oil suction filter element is installed in the oil suction filter of the oil pump to protect the oil pump and other hydraulic components to avoid inhaling pollution impurities, effectively control the pollution of the hydraulic system, and adjust the cleanliness of the hydraulic system.The return oil filter element is installed in the oil circuit of the hydraulic system to remove the metal powder and other mechanical impurities worn by the components of the hydraulic system to keep the oil circuit clean and extend the life of the hydraulic system. In the hydraulic system, it is used to filter the solid particles and colloidal substances in the working medium, and effectively control the pollution degree of the working medium.