Solid particle contamination level testing for oil samples is the most effective means to ensure the work reliabilities of hydraulic systems,and the metal micro pore filter membrane sensor has significant advantages in the testing method since it is not affected by the color of oil and the water and air bubble in oil during the particle contamination level testing process.The current situation on the development of metal micro pore filter membrane sensors,and the research status of the fouling mechanism and the contamination level testing model were reviewed.A new method to make the metal micro pore filter membrane sensors by using electro less nickel plating on plain weave stainless steel wire meshes with size of 600 was put forward,and a new idea for the establishment of contamination level testing model according to Ruths resistance theory was suggested.