Abstract: Polyvinylamine(PVAm)/polyethylene glycol(PEG) and PVAm/Poly(N-vinyl-γ-sodium aminobutyrate)(PVSA) polymer blends were prepared in this study. Composite membranes for the facilitated transport of CO₂ were prepared by using the dip-coating process with polymer blends as separation layer and polyethersulfone ultrafiltration membrane as substrate.The effects of blending composition on the structure and performance of the membranes were investigated by testing the crystallinity and gas permselectivity of membrane. The results showed that the proper blending of PVAm with PEG could reduce the membrane crystallinity and increase the effective permeation area and carrier content.The membrane with 10%(mass)PEG has the highest pure CO₂ permeation rate of 4.2×10^-9cm³(STP)•cm^-2•s^-1•Pa^-1 and highest CO₂/CH₄ ideal selectivity of 63.1 at 25℃ and 122.7 kPa of feed pressure. As for the PVAm/PVSA blend membrane, a proper blending composition could also improve the permselectivity of membrane. The membrane with 33%(mass) PVSA showed the highest CO₂/CH₄ ideal selectivity, while the membrane with 50%(mass) PVSA possessed the highest CO₂ permeation rate.