3-octyl-1-methyimidazole molybdenum acid peroxide ionic liquid [C8MIM]2[MO2O11] was synthesized with N-methylimidazole, n-octyl chloride, sodium molybdate and hydrogen peroxide as raw materials, and the product was characterized by 1H, 13C, FTIR and elemental analysis. The catalytic oxidation properties of the functionalized ionic liquid for dibenzothiophene were examined. The optimum experiment conditions (the volume of the model gas oil was 5 times of extraction agent, the mole ratio of oxygen to sulfur was 6:1, the dosage of catalyst was 5g per liter of model gas oil, the reaction temperature was 40 oC and reaction time was 30 min) of extraction coupled catalytic oxidation desulfurization were determined through the single factor analysis. The initial sulfur content (500 μg/mL) of the dibenzothiophene/ isooctane model gas oil dropped below 10 μg/mL, and the desulfurization rate was as high as 98.83% at the optimum condition. The system recycling performance was further investigated and the result showed the desulfurization rate was about 98.4% after 16 times repeated uses.