Abstract: Using polyamide acid as the pervaporation membrane material,and biatomic acid as the chemical modificatlon agent on the membrane,the separation characteristics of pervaporation membrane were studied.The suitable membrane(M2)was chosen to coulp the synthetic reaction of ethyl acetate,These experimental results were obtained. The conversion degree of acetic acid was more than 90 per cent.The new technology process of the esterification reaction of ethvl acetate might be proposed.