KH2PO4-WO3/γ-Al2O3 solid acid catalyst was prepared by the method of impregnation. According to the lactic acid dehydration production of acrylic acid reaction, some parameters including the load of WO3 on γ-Al2O3, the calcination temperature, the reaction temperature and lactic acid concentration were investigated. The results show that the conversion of lactic acid was 92%, and the selectivity of acrylic acid was 29% under the optimized preparation conditions.