Active carbons with various particle sizes (38-150, 300-500 and 800-1,200 μm) were modified by ionic liquids (ILs), and organic polymer was modified by acrylamide using a simple procedure, and these materials were applied to capture carbon dioxide (CO2). The CO2 adsorption amounts were calculated using a mass balance equation at three different temperatures (298.15, 308.15 and 318.15 K), respectively, and the influences of gas pressure, particle size and temperature on adsorption were discussed. Experimental results showed that the CO2 adsorption capacity of ILs-modified active carbons was better than amino-modified polymer, and the smaller particle size (38-150 μm) ILsmodified active carbons had the largest adsorption capacity at 298.15 K. Compared with previous research about polyethyleneimine (PEI)-modified silica gel, the adsorption amount of CO2 on ILs-modified active carbons has been greatly improved with lower cost.