With the continuous implementation of the smart city concept, smart cities have become an important tool for the country's new urbanization. Therefore, it is of great concern whether smart cities can help promote environmental sustainability. Most of the existing studies mainly discuss whether the proposed smart policies are effective for environmental sustainability, but the specific impact paths are not clear and long-term dynamic implications for policy have not yet been explored in depth
 This study takes 72 cities in China as an example, and divides the impact path of smart cities into four aspects: internet technology, science and technology innovation(STI), smart environment and smart people's livelihood. Environmental sustainability is measured by energy consumption and air pollution, and the cities are divided into characteristic cities according to resource endowment and economic development, and the dynamic impact on environmental sustainability is explored based on the Panel Vector Auto-Regression (PVAR) model. The results indicate that STI has a negative effect on air pollution in all cities in the early stage and a positive effect in the later stage, with the overall effect being more significant in developed cities. Internet development has an impact on air pollution control in developed cities, but the effect is positive in the early stage and negative in the later stage. STI and Internet technology have very significant results on energy consumption reduction. But for developed cities, the effect of STI on energy consumption is positive. This paper provides policy suggestions for the sustainable development of environment in cities with different characteristics in China from the perspective of smart city development.