Green Credit Subsidies and Green Total Factor Productivity—Evidence from the Chinese Market

Sustainable finance serves as a critical institutional lever for steering the national economic system toward a green transition, while the sustained rise in ecologically integrated output efficiency provides an important breakthrough for resolving the long-standing apparent tension between growth performance and ecological quality. Drawing on panel data from 30 provincial-level administrative units in China over the period 2005–2022, and employing a non-radial efficiency measurement index, a difference-in-differences identification strategy, and a synthetic comparative analysis method, this paper systematically examines the policy intervention effects and transmission mechanisms of the ecological loan interest compensation system on regional ecologically integrated output efficiency. The empirical results indicate that, within the sample observation window, following the implementation of the ecological loan interest compensation system, the ecologically integrated output efficiency of all provinces generally exhibited an upward trend, and the system exerted a significant positive driving effect on efficiency improvement. Transmission mechanism tests reveal that increased R&D and innovation activity, expanded sustainable credit scale, and optimization of industrial hierarchical structures constitute important intermediate links in the chain of policy effect transmission. Conditional effect analysis further reveals that the intervention effects of this system display a pronounced uneven distribution pattern across geographical space.