As urbanization continues to advance, scholarly attention to green infrastructure has expanded steadily; however, the way in which it contributes to better urban environmental quality remains insufficiently clarified. By combining the entropy-weight approach with regression analysis, this study employs panel data from 258 Chinese cities during 2008-2022 to examine empirically how the development of green infrastructure within urban landscape ecological design improves urban environmental conditions, while also identifying the moderating role and threshold characteristics of fiscal decentralization. The empirical evidence can be summarized in three aspects. First, green infrastructure construction exerts a significant positive effect on urban environmental quality, and this conclusion remains stable after a series of tests. Second, fiscal decentralization performs a moderating role, and a double-threshold characteristic is also observed in the relationship between green infrastructure and urban environmental improvement, with the estimated threshold interval being [0.35,0.64]. Finally, green infrastructure yields greater environmental benefits in the east and west and in big cities compared to central areas and small- and medium-sized cities. These results will be helpful to the governments in modifying fiscal decentralization in line with the prevailing local conditions, enhancing the growth of green infrastructure, and advancing environmental enhancement and green urbanization.
