To adapt to runoff evolution law in water source areas of South-to-North Water Diversion Eastern Route Project and give full play to hydrological reservoir capacity compensation effect of multiple water sources, a joint optimal dispatching model for project is established. The model is solved under three modes:dispatching line optimization, pre-allocated water volume optimization, and joint optimization of dispatching line and pre-allocated water volume. The optimized dispatching lines considering runoff evolution law in recent years and dispatching results of each optimization mode are obtained. A comparative analysis of different modes is conducted based on simulation results of original dispatching lines. The results show that compared with simulation results of original dispatching lines, optimized dispatching lines can effectively reduce water deficit in water receiving areas without impairing interests of original water receiving areas. Pre-allocated water volume optimization slightly increases water deficit of original water receiving areas, yet fully meets all water demands in eastern route area. Compared with single dispatching line optimization, the joint optimization of dispatching line and pre-allocated water volume further cuts down water deficit in eastern route area, proving more efficient and reasonable.