From green to gold: Synergistic enhancement of residents' well-being and ecological quality under China's "two mountains" pilots zones.

Achieving a harmonious symbiosis between economic prosperity and environmental sustainability remains a defining challenge for global sustainable development. This study investigates China's pioneering "Two Mountains" practice pilot zones (TMPZ) as an institutional model for resolving the "dualistic paradox" between growth and conservation. Using panel data from 1688 counties (2010-2023), we construct a multidimensional framework to evaluate residents' well-being (RWB) and evaluate its coupling coordination degree (RECCD) with ecological environment quality index (EEQI). A Double Machine Learning (DML) approach is further employed to identify the causal impacts of TMPZ on RECCD. The results reveal significant improvements in both RWB and EEQI, driving the RECCD from 0.4567 to 0.6345. All three indices maintain a consistent "Southeast-High, Northwest-Low" spatial pattern. Empirical evidence confirms that TMPZ designation not only improves ecological baselines and living standards but also effectively facilitates their synergistic evolution. These findings remain robust across various sensitivity checks. Heterogeneity analysis shows that the policy effects are most pronounced in eastern regions, non-poverty counties, and counties with high government financial investment. Mechanism tests indicate that TMPZ operates through three primary channels: intensifying environmental governance, stimulating green technological innovation, and facilitating the ecological transformation of industrial structures. By providing systemic evidence on how institutional innovation converts "ecological advantages" into "developmental momentum," this research offers a vital "Chinese Template" for developing nations striving to achieve the United Nations Sustainable Development Goals (SDGs) while balancing human prosperity and planetary health.