Accurate identification of ecological compensation areas and optimization of the spatial allocation of ecosystem services(ESs) are crucial for achieving ecological protection and socio-economic coordination in rapidly urbanizing regions. Taking the Poyang Lake urban agglomeration as the study area, this study focused on four representative ecosystem services—water yield, soil retention, carbon sequestration, and habitat quality—based on their ecological significance and close associations with other ESs. Using the InVEST model, we quantified the biophysical supply and socio-economic demand of these services in 2000, 2010, and 2020. Based on the InVEST model, the supply and demand of these services for 2000, 2010, and 2020 were quantified. The comprehensive supply-demand ratio index was constructed to identify the spatial patterns of services output and consumption. Furthermore, the breakpoint formula and field strength model were employed to characterize the intensity, direction, and spatial range of ecosystem service flows (ESFs), thereby elucidating their spatiotemporal dynamics. On this basis, a dynamic horizontal ecological compensation model was constructed by incorporating economic level and social development coefficients to calculate compensation amounts among counties. The results indicated that: (1) The spatial and temporal distribution of ecosystem service supply and demand was significantly heterogeneous. High supply values were concentrated in low mountain hills and wetlands, while high demand values clustered in central urban areas, showing a consistent increase over time. (2) The intensity of service flows and the total service value accepted by consumption areas exhibited a ‘first increase, then decrease’ pattern, with the central consumption area becoming more diverse in its service flow sources, showing a steady increase. (3) The number of ecological compensation recipients declined from 25 to 15, while the number of providers increased from 7 to 14. Compensation funds gradually concentrated in peripheral counties with rich ecological resources but relatively low socio-economic development, and the flows of compensation shifted from a radial to a more balanced spatial distribution pattern with wider coverage and improved equity.These findings offered a novel approach that integrated multi-temporal ESF evaluation and dynamic compensation modeling, providing a scientific basis for delineating compensation zones, quantifying ecological debt, and formulating targeted compensation policies. The findings could serve as an empirical reference for constructing equitable and efficient horizontal ecological compensation mechanisms in the Poyang Lake Urban Agglomeration and other ecologically sensitive, economically heterogeneous urban agglomerations in China. This research contributed to the advancement of ecological economics and spatial governance under the framework of ecosystem service flows and regional sustainability.