At present, cellulose nanocrystal (CNC) aerogels with high adsorption properties for CO2 are mostly prepared by the liquid phase method which leads to the problem of modifier loss. In this work, a novel amino CNC aerogel was developed by chemical vapor deposition using 3-(2-aminoethylamino)-propylmethyldimethoxy silane (APS) as the modifier, which improved the utilization ratio of the modifier while ensuring the CO2 adsorption performance. Herein, the as-prepared APS-CNC aerogel was characterized with elemental and functional groups and thermal, morphological, and structural characteristics by various measurements (X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and Brunauer-Emmet-Teller equation). It exhibited a porous network structure with low specific surface area (29.14 m(2)/g) and excellent thermal stability. Furthermore, the CO2 adsorption capacity of the CNC aerogel grafted with APS reached 1.5034 mmol/g (25 degrees C, 1 bar, and pure dry CO2 atmosphere). Meanwhile, the APS-CNC aerogel showed excellent CO2 adsorption/desorption recyclability after 10 cycles. The experimental results showed that the CNC aerogel modified by chemical vapor deposition had an important potential role as a biomass CO2 solid adsorbent.