Abstract: H₂O₂ and trichloroacetic acid were used in the catalytic oxidative desulfurization and the sulfon oxides produced were extracted from diesel with the polar solvent. The effects of technical parameters such as the volume ratio of oxidant to oil, the dosage of organic acid, the reaction temperature and the reaction time were studied. Furthermore, the power ultrasound was introduced to the process. The effects of ultrasonic frequency, intensity and time on the desulfurization were investigated as well. The optimal operating conditions are determined. The removal efficiency of sulfur compounds is up to 97.5% and the yield of diesel can reach 94.0%.