In this work, SBA-15-(DBU-X) was prepared by dipping 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) into the mesoporous channels of SBA-15 in an attempt to improve the CO2 adsorption. The synthesized SBA-15-(DBU-X) was characterized with scanning electron microscopy, thermogravimetric analysis, Brunauer-Emmett-Teller adsorption analysis, and other methods. Then the CO2 adsorption/desorption properties were investigated using a self-designed fixed-bed adsorption system. The results indicated that DBU could be loaded on the SBA-15 mesoporous molecular sieves effectively and that SBA15-(DBU-X) had good adsorption capacity toward CO2. SBA-15-(DBU-X) had good thermal stability at temperatures below 140 degrees C. At room temperature, with increasing loading of DBU and total flow rate of simulated flue gas, the adsorption of CO, on SBA-15-(DBU-X) had an increasing trend followed by a decrease. When the volume fraction ratio of CO2 and H2O was 1:1 in the simulated flue gas, SBA-15-(DBU-X) had an optimum capacity of CO2 adsorption. In addition, after six adsorption/desorption cycles, the adsorption capacity of CO2 was stable. Thus, SBA-15-(DBU-X) could be recycled.