Abstract: A scheduling chart of power generation, if designed by the specifications Design for Operation of Reservoir, usually has unreasonable points that cannot be removed even by repeated testing and modification. This article presents an improvement method and measures for eliminating such points and modifying the method recommended in the specifications. This new method adopts successive calculation of long series and unifies the calculations of one-year regulation and multi-year regulation of a reservoir. It can calculate the lower power output curve accurately and avoid the overlap between low output area and guarantee output area, improving the accuracy of power generation scheduling curves. Application to actual projects indicates that the method improves power generation scheduling chart in meeting different requirements of low output and firm output. The chart can be completed in one-time success with no need for repeated testing and modification and meet the reliability requirement of power design.