Catalytic oxidation is a non-HDS technology to remove sulfur compounds from diesel fuel. On the basis of catalytic oxidation and solvent extraction, ultrasound irradiation was introduced to provide energy for the reaction， which developed a completely new diesel oil oxidative desulfurization technology. The sulfides in Liaohe straight-run diesel fuel had been oxidized to sulfones with H2O2-formic acid as oxidant system was used in the process, the effects of reaction temperature, time and volumic ratio of oxidant and oil were investigated. The results show：under the condition of an ultrasonic frequency of 28 kHz|ultrasonic power of 200 W|the volumic ratio of H2O2 to formic acid 1∶1|extraction solvents N, N-dimethylformamide (DMF)|an extraction time of 10 min and the volumic ratio of extraction solvent to oil is 1∶2, its proper conditions are as follows: volumic ratio of oxidant to oil is 1∶10|reaction temperature is 50 ℃|oxidation time is 10 min|the rate of desulfurization is 87.8%.