Abstract: A series of active carbon-immobilized ionic liquid were prepared by the impregnation of 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide and characterized via FTIR, TG and SEM.The effects of impregnation concentration and time on pore structure distribution, CO₂ adsorption capacity, CO₂/N₂ selectivity and water resistance were investigated.Furthermore, the CO₂ adsorption behavior of activated carbon supported ionic liquid was discussed in detail.The results illustrate that the impregnation time is the key factor influencing the CO₂ adsorption performance.The active carbon-immobilized ionic liquid prepared with 0.24 mol/L impregnation concentration for 3 h can maintain the developed pore characteristics of activated carbon, resulting a better CO₂ adsorption capacity of 8.65% at 298 K and 0.1 MPa.Compared with the bare activated carbon, the sample modified byBmim TFSI can significantly enhance the CO₂/N₂ selectivity and the water resistance.The immobilized ionic liquids also have a faster CO₂ diffusion rate which is higher than pure ionic liquids two orders of magnitude.