Abstract: Traditional coordination methods for multi-objective scheduling of basin water resources typically approach the problem through multi-objective optimization, primarily relying on reservoir water levels. However, in plain-area basins characterized by dense river networks, high urbanization, and river-level-based control, scheduling demands vary over time, and water resource management exhibits a degree of independence. In such cases, traditional methods prove inadequate, necessitating coordination among different objectives from the perspective of river water levels. Based on a comprehensive analysis of the relationship between multi-objective scheduling and river water volumes, this study introduces the concept of river water level control lines. It summarizes the connotations and characteristics of control lines targeting flood control, water supply, and ecological protection, and analyzes their intra-annual variations. A coordination method for basin water resource scheduling based on these control lines is then proposed. Using the Qinhuai River Basin as a case study, a hydrodynamic-water quality model of the river network is constructed and solved, yielding a mean model determination coefficient of 0.87. Control line indicators under different hydrological frequencies are calculated: flood control lines at 7.85 m or below, water supply lines at 8.05 m or above, ecological lines at 6.90 m during flood season and 6.55 m during non-flood season. A coordination method integrating flood control, water supply, and ecological objectives based on the Dongshan Station water level is developed. Results demonstrate that by proactively adjusting river water levels, water resources in the network can be reasonably allocated, achieving coordinated multi-objective scheduling and enhancing comprehensive water resource utilization efficiency.