Abstract: The flooding mapping of small/medium-sized rivers is an important task of national flood and drought disaster survey in China,which is of great significance for disaster mitigation for which specific technical requirements to be made. Taking the Miluo River as an example, combining the content of technical requirements, the process of data collection and processing, flood analysis, flooding mapping, and outputs compilation was introduced. The results show that: the existing data, free public data, and technical means should be fully utilized to solve the river geometry data issue, meanwhile review and correction should also be conducted carefully; the selection of flood analysis options depends on the river geometry data, hydrological data and local flood simulation technical conditions; the spatial data of the outputs should be strictly processed to the specified coordinate and projection system specified in the technical reference, and enough attention should be paid to the administrative of transboundary rivers at the basin level in advance to ensure the smooth and successful integration of all outputs.