To analyze the carbon emission reduction effect of the sponge city construction model at Beijing Daxing International Airport, the carbon sources and sinks of sponge facilities under rainfall conditions in extra dry year, partial dry year, normal year, partial wet year, and extra wet year were calculated, and the pathways and effects of carbon emission reduction were analyzed. The results show that compared with the traditional construction mode, the carbon emission reduction of the sponge city construction model at Beijing Daxing International Airport for the whole year is 795.6~1804.0t of carbon dioxide emission equivalent, with an average annual reduction of 1221.2t. In different hydrological characteristics years, the carbon emission reduction rate of Daxing International Airport is 47.5%~58.7%, and the carbon dioxide emission equivalents of the sponge city construction model are reduced relative to airports of the traditional construction mode by an average of an annual reduction of 54.9%. The carbon dioxide emission equivalent increases with the increase of rainfall in a certain range, and the more precipitation, the greater the absolute reduction of carbon emission reduction of the sponge city construction model.