National Modern Agricultural Demonstration Zones （NMADZ） serve as crucial policy instruments for promoting the transformation and upgrading of agricultural development，yet their impact and underlying mechanisms on agricultural green development remain to be further explored.Based on panel data at the county level in Hunan and Hubei provinces from 2007 to 2022，this study employs a multi-period difference-in-differences model to evaluate the impact of the NMADZ policy on agricultural green development.The results indicate that the establishment of demonstration zones significantly improves the level of agricultural green development in pilot counties.The policy fosters green transformation indirectly by promoting agricultural technological innovation and invigorating new types of agricultural business entities.The effects of the policy were more pronounced in non-plains areas，economically developed regions，and counties facing less pressure of agricultural emissions reduction.Moreover，the policy effects intensify as successive waves of implementation unfold.This study suggests that policies related to agricultural transformation，such as those involving modern agricultural demonstration zones，should further strengthen the construction of platforms for green agricultural technological innovation at the county level，enhance policy support for the green transformation of new agricultural business entities，and advancing pilot policies in a region- and time-specific manner so as to transform institutional potential into actual momentum for high-quality agricultural development.