Revealing the dynamic coupling relationships and coupling levels among multiple indicators of the water resources carrying capacity system is crucial for enhancing the sustainable utilization of regional water resources and ensuring the steady development of the economy and society. In this study, the water resources carrying capacity system (WCCS) is divided into four subsystems: water resources, society, economy, and ecological environment, from which 16 representative indicators are selected. Regression coefficients and correlation coefficients are jointly used to classify the coupling relationships among the indicators. Finally, based on the sliding window method and network analysis, the dynamic trends of the coupling relationships among multiple indicators and the coupling level of WCCS are revealed. Taking Gansu Province as an example, the results show that the WCCS in Gansu Province has undergone a coupling-decoupling-recoupling pattern. After 2015, the strength of the positive coordination relationship has significantly increased, while the impacts of trade-off and negative coordination relationships have notably decreased. The key indicators in the positive coordination relationship are water resources development and utilization rate, urbanization rate, irrigation water consumption per mu, and per capita GDP, which have generally strengthened their driving effects on the positive coordination relationship over time. Most key indicators in the trade-off and negative coordination relationships have initially strengthened and then significantly weakened their driving effects on these two relationships over time. However, per capita daily water consumption still has a strong driving effect on the trade-off relationship and should be a key focus in future water resources management. The number of modules associated with the indicators of the WCCS has decreased from seven to five, indicating that although the system's coupling level has improved, there is still room for further enhancement. The research approach provides a new and effective way to objectively and comprehensively analyze the coupling and coordination of the system.