Abstract: With pressures from global warming and ecological degradation, it has become a core issue to establish a system for “intelligent, streamlined and efficient” green watershed assessment in sustainable development． In this paper a three-dimensional, nine-level framework integrating “temporal-spatial-spatiotemporal” dimensions is proposed for the Ganjiang River basin． The framework, (coupling AHP-EWM, M-K trend and abrupt change tests, piecewise-linear-fitting, Moran’s I, LISA clustering, Dagum Gini, standard deviation ellipses and triple convergence tests σ/α/β), comprehensively measures the Green Watershed Level (GWL) across 11 cities in Jiangxi Province from 2003-2022． GTWR analysis reveals driving patterns of six factors: human-water-energy-carbon-green-urban． Temporally, GWL exhibits sustained growth without abrupt changes, transitioning from slow to rapid growth from 2016． Spatially, GWL shows higher values in the south but lower in the north, with predominant “high-low” and “low-high” local clusters． Regional disparities decline in an “N”-shaped pattern, reflecting spatially unbalanced convergence． In spatiotemporal coupling, GWL center of gravity shifted southwestward, with distribution patterns evolving from clustering to dispersion． GWL of the 11 cities progressed from a median value in 4 cities and a low value in 7 cities in 2003 to a high-value range of 0.6–0.8 across all regions by 2020． Triple convergence of σ, α, and β confirms that GWL of the 11 cities is moving toward spatiotemporal equilibrium． Regarding driving mechanisms, marginal effects of six factors successively peaked and declined: population and carbon productivity shifted from positive to negative, water and forest marginal dividends rapidly diminished, positive effect of energy expanded at a slower pace, and urbanization effect passed its inflection point to approach zero． These findings provide historical references and precise policy guidance for high-quality developments in the Ganjiang Green Basin, offering methodological insights for other provinces as well．