Abstract In the emergent Anthropocene, interactions among water supply, power generation, and environment (WPE) systems are increasingly prominent due to the impact of human activity, the understanding of which calls for a holistic and dynamic coevolutionary perspective. Therefore, inspired by the nexus approach, this study investigates these three systems, integrated as a WPE coupling system. This paper aims to construct a system dynamics model from the perspective of socio-hydrology in order to predict and understand the coevolution trajectories and dynamics of the WPE coupling system. Firstly, the system dynamics model, which comprises the conceptual, stock and flow diagrams, and stylized models, is constructed to describe the dynamics of state variables of the WPE system. Then, the model is implemented in the WPE system of the upper Yangtze River basin of China. Results show that (1) the system dynamics model, which considers two-way feedbacks, is capable of modeling the coevolution of the WPE system and provides a powerful tool for exploring and understanding the emergent properties of the system; (2) the interrelation between economic development and environmental health is not entirely contradictory; however, if the economic development scale is not limited, their relationship will gradually evolve in the direction of contradiction; and (3) model parameters not only affect the timing and magnitude of the evolution trajectories of state variables but also their evolution patterns. These observations, obtained by modeling interactions across different systems, are insightful, improving our understanding of the coevolution of the WPE coupling system.