A solid acid derivative of beta-cyclodextrin was synthesized as an adsorbent for CO2 capture. The adsorption characteristics, such as adsorption capacity, selectivity, and uptake rate, under different temperatures and gas pressures were analyzed. The results from scanning electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller (BET) sorption, Fourier transform infrared spectroscopy, andthermogravimetric analysis indicated that the dehydration and grafting of sulfonic groups changed the structure of beta-cydodextrin aggregates into a relatively homogeneous porous structure with a concave convex surface. Meanwhile, the specific BET surface area and pore volume of the solid acid derivative were increased by 40 and 37 times compared to beta-cyclodextrin aggregates. Thereby, the performance of the solid acid derivative of ficydodextrin toward CO, sorption was significantly enhanced, in which CO, adsorption capacity at 3.5 bar was increased to 1.78 mmol/g and the selectivity of CO2 over N-2, O-2, and CH4 at 298 K reached 7. Interestingly, there was no adsorption of nitrogen on the as-prepared solid acid derivative at 77 K based on BET sorption. Lowering the temperature is disadvantageous for N-2 adsorption but helpful to promote CO2 capture, so that the high selectivity of CO2 to N-2 sorption can be achieved.