Azelaic acid has been synthesized from industrial oleic acid by using potassium permanganate oxidation in this paper. In order to find the best condition of synthesis, the straight-cross method has been used to arrange for the experiment, the product has been studied by infrared spectroscopy. The best condition was that the proportion of oleic acid to potassium permanganate was 0. 50: 1, the cost of sulfuric acid was 10 mL, the cost of tetrabutylammonium bromide was 1. 0 g , emulsified by ultrasonic for 10 min, the yield was increased to 57% at 50 ℃, the mild reactions have industrial importance .