Abstract: The realtime flood risk analysis can play an important role in flood emergency and disaster relief, but it is difficult to fully realize the real-time flood risk analysis because of the some factors, such as technical conditions, data base and so on. This paper summarizes a set of realtime flood risk analysis method, including basic datasets, model methods, and technical program. Taking the realtime flood analysis of the Shu River in the tributary of Ganjiang River in June 2018 as an example, the model method is tested. The results show that the method proposed in this paper is effective and feasible, and can play an important role in flood prevention,emergency, command and dispatch. Finally, it points out that the working mechanism, support condition, cooperation with other departments, and other restrictive factors still exist in the implementation of realtime flood risk analysis. Some suggestions are given to the department organization, operation mechanism and cooperative operation mode for those problems.