In order to improve the CO₂ separation performance of polyether copolyamide (Pebax) membrane, amino acid ionic liquid (AAIL) was synthetized and used to prepare AAIL/Pebax blended membranes. The AAIL/Pebax membranes were characterized by FT-IR, TGA, DSC and XRD. And the CO₂ gas separation performance test was performed so as to determine the influence of the content of amino acid ionic liquid, operating pressure and temperature on gas permeability. The results show that the permeability of CO₂ and selectivity of CO₂/N₂ are improved with adding amino acid ionic liquid. The permeability coefficient of CO₂ is 101.03 Barrer, and the selectivity of CO₂/N₂ is 91.84 when the AAIL mass fraction is 0.8% . Compared with the pristine Pebax1657 membrane, the permeability coefficient of CO₂ is increased by 66.47%, and the selectivity of CO₂/N₂ is increased by 86.14%, exceeding the 2008 Robeson’ s upper bound.