Accurate identification of ecosystem service (ES) supply-demand patterns was critical for optimizing ecological spatial structures and enhancing regional ecological governance capacity. This study focused on the Poyang Lake Urban Agglomeration in China and developed a comprehensive multi-scale analytical framework under the water-energy-ecology(WEE) nexus to systematically assess ES supply and demand relationships. Four key ES types-water yield, carbon sequestration, soil retention, and habitat quality-were selected because they represent essential ecological processes and resource flows that underpin regional sustainability and environmental security. The ecological supply and demand volumes, as well as supply-demand ratios, were quantified for the year 2020 using the Revised Universal Soil Loss Equation (RUSLE) and Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) models. To characterize spatial heterogeneity and clustering patterns, spatial autocorrelation indices, hotspot and coldspot analyses, and Spearman correlation coefficients were applied at three nested scales: grid, county, and municipal levels.Based on the spatial matching of supply and demand, a coupling coordination model was employed to diagnose the degree of alignment between ecological capacity and socioeconomic needs across scales. Additionally, a Self-Organizing Map Feature (SOMF) clustering method was introduced to further classify dominant ES functions within each county, enabling a more refined understanding of functional differentiation and localized management priorities. The results showed that: (1) ES supply in 2020 exhibited a spatial pattern of higher values in the east and periphery and lower values in central areas, whereas demand was concentrated in urban cores, revealing a significant spatial mismatch; (2) Supply-demand patterns displayed strong scale effects and service-specific heterogeneity, with greater coordination at municipal/county levels and more pronounced spatial heterogeneity at the grid scale; (3) The zoning system identified three municipal-level functional zones—urban expansion and ecological restoration areas, ecological reshaping and industrial transformation areas, and ecological barrier and functional conservation areas—while county-level zones provided more detailed ES function management strategies. The integrated zoning framework delineated three municipal-level functional zones—urban expansion and ecological restoration areas, ecological reshaping and industrial transformation areas, and ecological barrier and functional conservation areas. County-level divisions provided more detailed management recommendations to enhance ES supply-demand balance and strengthen ecological resilience. This multi-scale approach advances the theoretical understanding of ES supply-demand dynamics within the WEE framework and provides robust, actionable insights for regional ecological management, resource allocation, and spatial planning. This study provided a comprehensive multi-scale analysis of ES supply-demand dynamics and proposed a multi-tiered ecological spatial optimization framework offering theoretical insights and practical guidance for regional ecological management, resource allocation, and spatial planning.