The oil particle counter adopts the counting principle of photoresist (shielding) method and is a detection instrument specially used for online measurement of oil cleanliness level and particle counting. It has the advantages of small size, light weight, fast detection speed, high precision and good repeatability. It is suitable for hydraulic oil, lubricating oil, transformer oil, water-based fluid and other media, and is widely used in engineering machinery, metallurgy, electric power, military industry, aerospace and other fields.