The problem of global warming caused by the rapid growth of carbon emissions has attracted more and more attention in all countries, so it is of great importance to develop feasible CO2 capture materials. In this paper, kaolinite is used as raw material, to prepare mesoporous silica carrier (KNH) with the method of calcination-alkali activation-acid etching. Then the pentaethylenehexaamine (PEHA) functionalized mesoporous silica (KNH-PEHA) was synthesized via impregnation. The prepared samples were characterized by X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and N2 adsorption-desorption isotherms treated by BET (Brunauer-Emmett-Teller) analysis. And the solid adsorbent is also used to study the adsorption property of carbon dioxide (CO2). The results indicate that the structure of PEHA-loaded KNH is not changed, but its carbon dioxide adsorption capacity is improved. When the adsorption temperature is 25 ℃, the CO2 adsorption capacity of KNH is 147.39 cm3/g, and the CO2 adsorption capacity of KNH (KNH-P-30) with a mass percentage of PEHA of 30% reaches 389 cm3/g, which is much higher than that without PEHA modified KNH adsorption. At the same time, it express the adsorption mechanism of the solid adsorbent for CO2, which provides a new idea for the application of kaolinite in the field of gas adsorption.