高水平开放自贸区政策是否提升了城市绿色创新效率OACHSSCDCSTPCD

This paper used balanced panel data from 276 prefecture level cities in China from 2009 to 2022,and took the imple-mentation of the policy of high-level opening-up free trade zones as a quasi-natural experiment.Using the multi-period DID meth-od and spatial Durbin model,this paper explored the impact,mechanism,and spatial spillover effects of the policy of high-level open-ing-up free trade zones on the urban green innovation efficiency.The results indicated that:①The policy of high-level opening-up free trade zones in China has significantly improved the urban green innovation efficiency through scale and structural effects,which was conducive to high-quality and sustainable urban development.②Coastal cities benefited more from the green innovation efficiency im-provement of the policy of free trade zones compared to inland cities.And the higher the city level was,the better it could seize develop-ment opportunities from the high-level opening-up practices represented by the establishment of free trade zones,finally improving the green innovation efficiency of cities effectively.③In terms of spatial innovation spillover effects,the policy of high-level opening-up free trade zones has had a positive direct and indirect impact on the urban green innovation efficiency,and there was also a positive spatial spillover effect.