At the same time, ammonium fluoride solution and lanthanum nitrate solution were added to hydrolyze tetrabutyl titanate, and F-La-co-doped amorphous TiO2, namely F-La-TiO2 (Am), was prepared, and applied to the photocatalytic oxidative desulfurization of simulated diesel fuel with DBT (dibenzothiophene) as the probe. The characterization results of XRD, FT-IR, XPS, UV-vis, SEM, PL and VB-XPS showed that after successful co-doping of F and La, the electronegativity of F narrowed the band gap of the catalyst, and the formation of La-O bonds provided more oxygen vacancies, promoted the formation of impurity energy levels, and effectively inhibited the recombination of electrons. Under the optimized operating conditions, that is, the catalyst dosage is 1 wt% (based on simulated diesel), the O/S molar ratio is 15:1, the agent-oil ratio (v/v) is 1:1, and the desulfurization rate reaches 94.10%, which is 12.71%, 9.52% and 27.5% higher than the amorphous La-TiO2(Am), F-TiO2(Am) and anatase F-La-TiO2(An), respectively. The catalyst was reused four times, and the desulfurization rate could still reach more than 85%, and the mechanism studies showed that the main active intermediate species were superoxide radicals (· O2-) and holes (h+).