A series of dawson type aluminiumphosphotungstates supported on MCM-41 molecular sieve（AlH3P2W18 O62?nH2O/MCM-41）were prepared by immersion process and was used in the synthesis of acetylsalicylic. The structures of catalysts were characterized by FT-IR, XRD, SEM , EDX, BET, NH3-TPD,N2-TPD and TG-DSC. Influences of amount of AlH3P2W18O62?nH2O loading, dosage of catalyst, the mole ratio of reactants, reaction temperature, reaction time and reusability of catalyst on the reaction were investigated. The results indicated that the AlH3P2W18O62?nH2O was evenly loaded on the MCM - 41 carrier and existed in the form of Dawson structure. Compared with AlH3P2W18O62?nH2O, the high specific surface area and thermal stability of supported catalyst (30% AlH3P2W18O62?nH2O/MCM-41) increased, but the acid strength of supported catalyst reduced. The supported catalyst showed honeycomb shape and had both Br?nsted and Lewis acid centers. Under the optimal conditions,i.e, loading amount of AlH3P2W18O62?nH2O of 30%, w (30% AlH3P2W18 O62?nH2O/MCM-41）=4.1% (relative to the dosage of total reactant), reaction temperature of 80℃, reaction time of 30 min, the yield of aspirin could reach 96.3%. The catalyst has good reusability and the yield of aspirin could reach 80.6% after six cycles. 30% AlH3P2W18 O62?nH2O /MCM-41 is the efficient and environmental friendly catalyst in synthesizing aspirinwith good catalytic activity and reusability.