In the Study on Water Dynamics Rules in the Yellow River and Dualistic Dynamics Model, a dualistic dynamics model of water resources was established by coupling a distributed hydrological model for large river basins (WEP-L) and a water allocation and regulation model (WARM). Concepts of water resources both in narrow and generalized senses were proposed, and an approach for multi-criterion and dynamic assessment of water resources was suggested. The achievements have important reference values for objective evaluation of ecological soil and water conservation, hydrological effects of land use change such as farmland construction, the Yellow River treatment planning and water security strategy.