Objective：To develop a method for the purification and identification of human Pregnancy-associated plasma protein A. Methods：Pregnancy-associated Plasma Protein A fraction was isolated and purified by DEAE-Sepharose CL-6B ion-exchange and heparin-Sepharose Cl-6B affinity chromatography， denatured SDS-PAGE and Western blot method respectively. Results：The expressed protein, with a relative molecular weight of 200 kD, showed specific reaction with McAb to pregnancy-associated plasma protein A. Conclusion：Pregnancy-associated plasma protein A could be successfully isolated from pregnancy serum.