In order to relieve the amine agglomeration phenomenon in solid amine adsorbent and realize the efficient CO2 capture, a novel double-functionalized adsorbent was synthesized by grafting 3-aminopropyltriethoxysilane and impregnating tetraethylenepentamine, using original mesoporous silica molecular sieves as support. The effects of organic amine loading, gas flow rate and adsorption temperature on CO2 adsorption properties of adsorbent were studied. The results show that SBA-15(p)-AP-70T modified with 70% TEPA has the maximum N content (15.81 mmol/g) and the maximum saturated adsorption capacity (5.69 mmol/g) at 75 degrees C, Moreover, the CO2 adsorption capacity of this adsorbent can still remain about 5.2 mmol/g after 15 adsorption/desorption cycles. It is mainly because that the grafted APTES and residual P123 in the support pore provide space and hydrogen bonding functional groups for TEPA dispersion and fixation, while reduce the loss of TEPA during the cycle process. Therefore, compared with adsorbent modified by only TEPA, the adsorption capacity and stability of this adsorbent can be effectively improved. In addition, kinetic studies indicate that CO2 adsorption on SBA-15(p)-AP-70T is mainly chemisorption. According to the in situ DRIFTS results, CO2 adsorption mechanism on SBA-15(p)-AP-70T adsorbent is consistent with the zwitterion mechanism.