Two kinds of fixed carrier membrane materials containing secondary amine and carboxyl groups which can be used as carriers of CO2 were prepared. One was poly(N-vinyl-7-sodium aminobutyrate)(PVSA), which was obtained through the hydrolysis of polyvinylpyrrolidone (PVP) synthesized with N-vinylpyrrolidone(NVP) by radical polymerization. The other was poly(N-vinyl-7-sodium aminobutyrate-co-sodium acrylate)(VSA-SA), which was obtained through the hydrolysis of copolymer of N-vinylpyrrolidone and acrylamide(AAm) (NVP-AAm). The composite membranes were developed with PVSA or VSA-SA as active layer and polysulfone (PS) as support membranes. The permeation rates of pure CO2 and CH4 gas as well as binary mixtures of CO2/CH4 through the composite membranes were measured. The results show that the composite membranes present better CO2 permeation rates than other fixed carrier membranes do reported in literature. For example, at 26℃, 1330 Pa of CO2 pressure, the PVSA/PS composite membrane displays a CO2 permeation One was poly (N-vinyl-7-sodium aminobutyrate) (PVSA), which was obtained through the hydrolysis of polyvinylpyrrolidone ( PVP) synthesized with N-vinylpyrrolidone (NVP) by radical polymerization. The other was poly (N-vinyl-7-sodium aminobutyrate-co-sodium acrylate) vinylpyrrolidone and acrylamide (AAm) (NVP-AAm). The composite membranes were developed with PVSA or VSA-SA as the active layer and polysulfone (PS) as support membranes. The permeation rates of pure CO2 and CH4 gas as well as binary mixtures of CO2 / CH4 through the composite membranes were measured. The results show that the composite membranes present better CO2 permeation rates than other fixed carrier membranes do reported in literature. For example, at 26 ° C, 1330 Pa of CO2 pressure, the PVSA / PS composite membrane displ ays a CO2 permeation