The oxidation⁃extraction process was used to desulfurize of the visbreaking diesel oil, O3 was used as oxidant, formic acid was used as catalyst, and polar oxides such as sulfoxide and sulfone were extracted and separated from diesel oil by polar organic solvent. The effects of oxidation time, oxidation temperature, ratio of extractant to oil and amount of formic acid on the desulfurization rate of diesel oil in the reaction system were investigated, and the optimum reaction conditions were determined. The results showed that the sulfur content of visbreaking diesel oil decreased from 4 980 μg/g to 490 μg/g and the desulfurization rate was 90%. By comparing the properties of visbreaking diesel oil before and after oxidation, it can be concluded that the oxidation⁃extraction method can also improve the chromaticity and acidity of visbreaking diesel oil.