Abstract: Studying the trade-off and synergistic relationship between ecosystem change and urbanization development in the Yangtze River Delta Region is highly important for clarifying the relationship between urbanization development and ecological environment change and for proposing differentiated ecological environment protection and urban development suggestions. Based on the MOD17A3 NPP and the Nightlight Dataset (PANDA), the temporal and spatial trends in the net primary productivity and light intensity of ecosystems in the Yangtze River Delta and their trade-offs and synergies were comprehensively analyzed by using the correlation coefficient method and trend scenario combination. The results show that the ecological quality in the Yangtze River Delta improved, and the NPP increased from 447.19 g·m^-2·a^-1 in 2000 to 529.92 g·m^-2·a^-1 in 2020. Urbanization in the Yangtze River Delta Region has continued to increase, with light intensity increasing from 436.79 in 2000 to 1 012.06 in 2020, and the area with an increasing trend accounted for 91.79% of the total area. The spatial distribution shows that the agglomeration effect of the downtown area spreading to the periphery decreases and gradually increases with decreasing distance from the city center. High-quality coordinated development of the economy, society and ecological environment has become the main development trend in the Yangtze River Delta Region, and areas with significant increases in both light intensity and NPP account for 33.93% of the total area. Among them, 61.44% of the regions exhibited synergistic relationships, which were mainly distributed in the areas around the cities in the Yangtze River Delta Plain. There are fewer areas with a trade-off relationship, and these areas account for 4.67% of the total area, with the manifestations of significant increases in light intensity and significant decreases in NPP, and they are mainly located in areas of rapid urbanization, such as Shanghai and Suzhou-Wuxi-Changzhou metropolitan area.