Abstract: Taking Dingbian County,Shaanxi Province as the research object,this paper constructs an evaluation system of coupled indicators for "water resources-society-economy-ecology".The combined weights are determined by using the entropy weight method integrated with the analytic hierarchy process(AHP),and the TOPSIS model is employed to quantitatively evaluate the water resources carrying capacity of Dingbian County from 2015 to 2024.Furthermore,this study analyzes the synergistic variation patterns of each subsystem and assesses the evolution characteristics and driving mechanisms of water resources carrying capacity in Dingbian County,Shaanxi Province.The results show that:In terms of temporal scale,the overall water resources carrying capacity of Dingbian County presents a stepwise decreasing trend,changing from weak carrying capacity through a critical state to overloading,with a significant overall downward trend and continuously increasing water resources pressure in the county;in terms of influencing mechanism,the water resources system acts as the core controlling factor of the county's water resources carrying capacity,and its combined weight is much higher than that of other evaluation systems,among which the proportion of groundwater resources,agricultural irrigation water consumption per mu,annual rainfall and regional per capita GDP are the four core influencing factors;in terms of system synergy,the carrying capacities of the four subsystems show a synchronous downward trend,reflecting the high coupling between various systems and water resources in the county,forming a vicious cycle characterized by " water shortage-development restriction-ecological degradation ".The research results provide a transferable methodological reference and decision-making basis for carrying out dynamic carrying capacity evaluation,identifying system contradictions and formulating collaborative governance strategies in other water-scarce areas of the same type,and offer scientific support for the refined management of the " Four Waters Four Determinations" principle at the county level under the strategy for ecological protection and high-quality development of the Yellow River Basin.