In the context of"double carbon",our country is faced with great pressure of environmental pollution such as carbon emissions.Based on the panel data of enterprises in China from 2009 to 2021,this paper investigates the impact of smart city construction on the carbon emission level of enterprises by using multi-stage differences-in-differences method,taking enterprise carbon emission as the research object.The research shows that smart city construction can reduce the carbon emission level of enterprises by promoting green innovation and optimizing industrial structure.In the further study,this paper explores whether this impact has spillover effect.The research results show that the carbon emission reduction effect of smart city construction has a significant positive spillover effect on surrounding cities.Heterogeneity test shows that such spillover effect is more significant in non-state-owned enterprises and non-high-tech enterprises.