Abstract: An immobilized metal ion affinity membrane was prepared by plasma-induced graft polymerization of glycidyl methacrylate (GMA) onto a porous polypropylene(PP), followed by chemical conversion of epoxide group of the GMA grafted membrane into an iminodiacetate(IDA) group, and chelation with copper ion. The effect of plasma discharge condition, GMA monomer concentration and grafting time on the degree of GMA grafting was studied and the optimum condition for plasma treatment of membrane was:10 W for 30 s, and that for grafting is 30 h at a concentration of 1 mol· L -1 GMA.Under this condition, a maximum grafting degree of 13.28% was obtained. The spectra of IR and XPS shows that GMA and IDA had been attached to the PP membrane after grafting and coupling. The nonselective adsorption of PP membrane had been significantly reduced after the H 2SO 4 treatment of the IDA coupled membrane. Finally, the isotherm adsorption of bovine serum albumin (BSA) on the immobilized metal ion affinity membrane was measured and the adsorption capacity of BSA increased with the degree of grafting. When BSA concentration was 1080 μg·ml -1 ,the adsorption ability of the affinity membrane with a grafting degree of 5.3% was nearly twice as much as that membrane with a grafting degree of 4.66%.