As one of the most rapidly urbanizing and densely populated areas in the world, the landscape pattern of green spaces and urban thermal environments in the Yangtze River Delta has experienced significant changes due to urbanization. The arrangement of green space is crucial for the urban thermal environment and residents’ health. How the influence of green space landscape pattern on changes in land surface temperature varies with spatial and temporal scales, and how the interaction of landscape indices affects the land surface temperature, are important scientific issues that require further study and analysis. Using landscape pattern indices, correlation analysis, and geographic detectors, this study revealed the evolving dynamics of green landscapes and surface temperature patterns in the Yangtze River Delta Region from 2000 to 2020, while exploring the relationship between green landscape patterns and the heat island effect. The results show that from 2000 to 2020, the area proportion of green space decreased by only 0.9%, but the spatial distribution is more concentrated, and the degree of fragmentation has been weakened. The area proportion of urban heat islands increased by 2.7%, with apparent intensification, gradually gathering into regional heat islands. The result showed that the contribution of greenspace area proportion to land surface temperature (q=0.168) was significantly greater than that of other greenspace landscape index (q=0.091). From 2000 to 2020, the contributions of green space area proportion, aggregation, and the most extensive patch index gradually increased. But with the expansion of the analysis unit, their contributions gradually diminished. The interactions of greenspace landscape indices consistently enhance the explanatory power for land surface temperature, either through nonlinear enhancement or bivariate enhancement. At smaller spatial scales, PLAND has the strongest interaction with PD and NLSI. It is suggested to prioritize the layout of “coverage - shape - connectivity” compound green spaces at more minor spatial scales to maximize the thermal environment effect of green landscape patterns. This study provides ecological methods and scientific reference for optimizing and regulating the landscape pattern of urban green space, to mitigate regional urban heat risks.