Abstract: A new amino-acid functionalized heteropoly tungstate (Ala₃PW) was prepared with alanine and phosphotungstic acid as raw materials. The structure of Ala₃PW was characterized by XRD, FT-IR. The removal of dibenzothiophene (DBT) in model oil was studied by using Ala₃PW as catalysts, hydrogen peroxide as oxidant and imidazolium tetrafluoroborate (HMIMBF₄) as the extractant. The influence of reaction temperature, the amount of catalysts, the molar ratio of O/S(H₂O₂/DBT), the amount of extractant and types of thiophene on the desulfurization efficiency were investigated. The results indicated that under the optimal reaction conditions of 10 mL model oil, 0.04 g of Ala₃PW, O/S(mol ratio) =6, V(HMIMBF₄)/V(oil)=0.6, reaction temperature of 50 ℃ and reaction time of 180 min, removal of DBT was found to be 98.2%. The catalyst could be recycled 4 times without a significant decrease in activity.