Abstract: The HMCM-22 molecular sieve was modified with phosphotungstic acid (PW) by an impregnation method, and the resulting composite catalysts were characterized by XRD, SEM, FT-IR. The results indicated that there was no change in the original structure and characteristics of the modified HMCM-22 molecular sieve. The productivity of monododecyl ester was improved significantly for the synthesis of mono-alkyl phosphate (MPA) through esterification of dodecanol and phosphorus pentoxide at a molar ration of 2/1, indicating that the esterification was promoted synergistically by the active center of composite catalysts, thus resulting in excellent catalytic performance. For the composite catalyst loaded with 4 wt.% PW, a high productivity of 90% was achieved when the amount of water was 9 g, the amount of composites catalysts in total reactants was 1.5 wt.%, the reaction temperature was set at 90 °C, and the reaction time was set as 4 hours. This suggests that the PW/HMCM-22 composite molecular sieve has an excellent catalytic effect.