Using 50% aqueous hydrogen peroxide as oxidant, 2-propanol as cocatalyst, 9,10-dihydroxystearic acid was synthesized with oleic acid as raw material and tungstic acid as catalyst. The solvent was removed by vacuum distillation, and then peracetic acid was added. After reacting for 60 min under microwave irradiation, the product was extracted with hot water. The yield of the acid was 70.5% and the purity of the acid was up to 97.76%. When reacting for 120 min under microwave irradiation, the yield of acid was increased to 74.6 %.