Abstract: Application analysis on contaminated concentration detection technology which is based on the density property of oil product is conducted. Temperature compensation for density of single-oil product must be done when contaminated density is detected real-timely and contaminated concentration is converted, and that shall be served as the base of contaminated cutting. A new computational method which is named arithmetic progression recursion approximation is put forward and the shortcoming of traditional computational method is avoided. A calculation program is worked out and hand-held reduction apparatus is designed meanwhile.