An ordered mesoporous carbon CMK-3 was synthesized by the template method, and was used to adsorb CO2. The synthesized CMK-3 was modified by immersion with chitosan solution to introduce surface nitrogen-containing functional groups. The effect of CMK-3 surface modification on CO2 uptake capacity was investigated. The texture characteristics of the CMK-3s were determined by small angle X-ray scattering analysis (SAXS), transmission electron microscope (TEM) and nitrogen adsorption analysis. The surface functional groups of the CMK-3s before and after modification were determined by an X-ray photoelectron spectroscope (XPS). CO2 uptake capacity of the CMK-3s was obtained by a gravimetric adsorption apparatus at room temperature under atmospheric pressure. Experimental results revealed that both nitrogen functional groups (pyridine and pyrrole) and supermicropores (