Abstract: Flood frequency analyses of small and medium-sized catchments provide important basis for flood risk analyses and management. This paper puts forward the idea of compiling flood frequency atlas in small and medium-sized mountainous catchments. The hydrological regionalization will be divided and adjusted through comprehensively considering the impact of climate and underlying surface conditions on runoff generation and confluence processes. Flood frequency analysis will be conducted at both station scale and regional scale using historical and investigated flood data. Meanwhile, for small and medium-sized catchments in mountainous regions, flood frequency analysis will be conducted mainly through the distributed hydrological modelling approach on basis of the results of rainstorm frequency analysis and high resolution topographic and geomorphic data. The flood frequency atlas and database will be constructed for small and medium-sized catchments under various frequencies. This study is expected to provide basic supports for flood risk assessment and early response, and promote improvement of flood disaster prevention level.