Smart cities are a key engine for comprehensively advancing Chinese-style modernization and driving high-quality economic development in the new era. To evaluate the implementation effects of smart city pilot policies, in this paper the "smart city" is studied based on panel data from 217 prefecture-level cities spanning Year 2003 to 2021 to build the difference-in-differences model and investigate the green development effects of smart cities from both theoretical analysis and empirical testing. The results indicate that smart city pilot policies significantly promote urban green development. In the central and western regions, the policy exerts a stronger driving force on green economic growth compared to the eastern regions; and by optimizing government resource allocation methods and promoting green industrial upgrades, pilot cities achieve green development. For policy formulation and practical advancement for construction of smart city, the findings of this paper can provide a new sustainable development pathway integrating resource allocation optimization, coordinated regional development, and institutional standard sustainability; and a series of targeted policy recommendations and it can provide theoretical references for evaluating the ecological benefits of smart cities and facilitating the coordinated development of smart cities and the green economy