Poly (acrylonitrile-co-vinyl pyrrolidone-co-acrylic acid) (P(AN-VP-AA)) was synthesized via free radical copolymerization, and used to blend with polyethersulfone (PES) to prepare PES membrane, and followed by grafting bovine serum albumin (BSA) onto the surface of the membrane. Compared to binary copolymers, such as P(VP-AA) and P(AN-AA), the blending amounts of the terpolymer and the BSA grafting amounts increased. To confirm the existence of BSA on the membrane surface, micro $BCA^{TM}$ protein assay, XPS and ATR-FTIR analysis were used. The water contact angle, protein adsorption and platelet adhesion were obviously decreased after grafting BSA onto the membrane surface. Furthermore, the antithrombogenicity of the modified membranes, such as the prothrombin time (PT) and activated partial thromboplastin time (APTT) increased, and the cytocompatibility increased. These results indicated that the BSA modified PES membranes had a good biocompatibility.