Abstract: Pore-expanded mesoporous silica (MCM-41) was synthesized and employed as a host for grafting 3-［2-(2-aminoethylamino)ethylamino］propyl trimethoxysilane to obtain an amino-functionalized mesoporous silica composite. The pore-expanded MCM-41 before and after amine immobilization were characterized by N₂ adsorption-desorption measurement, fourier-transform infrared spectroscopy, and thermal gravimetric analysis. CO₂ capture performances of samples were then examined. Results showed that surface area, pore volume, and pore size of amino-functionalized pore-expanded MCM-41 composite were lower than those of pore-expanded MCM-41. At the same time, amino-functionalized pore-expanded MCM-41 composite showed much higher CO₂ adsorption capacity than that of pore-expanded MCM-41 only (their CO₂ capture capacity is 28 mg/g and 76 mg/g, respectively), and excellent stability in the cyclic CO₂ adsorption-desorption experiments