A summary is firstly made on the research achievements of key technical issues in the flood prevention and the emergency management at home and abroad. In view of the characteristics of small and mediumsized rivers such as large quantities, frequent floods, and severe disasters in China, this study discusses the construction of high spatialtemporal resolution rainfall field and shortimpending accurate forecasting, the fine and intelligent flood forecasting, the realtime flood risk assessment and emergency disposal, the quality control of hydrometeorological data, the cloud platform construction and so on. Through the discussion of key scientific problems, a train of thought can be provided on key technologies of flood prevention and emergency management.