Nano-titanium dioxide (TiO2) was synthesized by sol-gel method and was used as photocatalyst for photocatalytic oxidation desulfurization of fuel oil. Et3NHCl·FeCl3 was synthesized as low-viscosity ionic liquid (IL) and used as efficient extractant and oxygen in air was used as oxidant. Nano-TiO2 was analysis by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The factors influencing the desulfurization rate of model oil such as oil ratio, the amount of titanium dioxide, the air pass into the volume and photocatalytic time. The results show that the desulfurization rate could reach 98.5% in 3h under below conditions: TiO2 amount was 0.1g/100mL, air flow was 500 ml / min and V(IL):V(oil)=1:1.