Abstract: Since the reform and opening up, China has achieved rapid economic growth. However, there are many problems with serious air pollution. Air pollution has become one of the important factors restricting the sustainable development of economy and society. Based on the panel data of 299 prefecture-level cities in China from 1998 to 2018, this paper uses “difference-in-differences” method to prove that smart city construction can reduce the air pollution represented by PM_2.5 and promote the economic growth represented by night-light data. And heterogeneity research shows that smart city construction is more effective in reducing the haze pollution in the north of China, general city and samples of cities that are close to provincial capital cities. Further study shows that the construction of smart cities has reduced the level of smog by promoting technological innovation, deepening the digitalization of inclusive finance, increasing the number of bond issues and reducing the intensity of industrial land sales. The above conclusions show that the construction of smart city, as an important part of improving national governance capabilities, is of great significance for achieving rapid development in China.