In order to solve the problems of lack of runoff data and incomplete data in the process of ecological flow research in some areas, this study took Jincheng City as a typical study area, used the method of global natural runoff simulation data, and used the vector river network confluence model to simulate the runoff data. On the basis of this data, the Tennant method in the hydrology method was used to calculate the ecological water demand of the Jincheng River, and the design guarantee rate of the ecological flow (water volume) target was scientifically and reasonably determined according to the water resources conditions, engineering regulation and control ability, and the importance of ecological protection in the basin, and the analysis of the ecological flow guarantee rate and satisfaction of the river was made. The future implementation direction of the optimal allocation of water resources in Jincheng City was determined, and new research methods and ideas were provided for the study of ecological flow in other ungauged basins.