Abstract: Based on the analysis of the basic,characteristics of the medium and small river basins,this paper firstly presents the objective and significance of the flood control planning in these river basins.Then the main contents and steps of flood control planning are introduced,and the development and application of flood control planning decision support system in medium and small river basins are described in detail.The application of the decision support system in medium and small river basins will inevitablely promote the research,simplify the process for the flood control planning in medium and small river basins,and also make the flood control planning in these river basins more accurate and scientific.