Accurate and effective flood forecasting is of great practical significance for controlling the flood disaster.Combined with the basin reality and the data mining technology，this paper gives the definition of automatic identification of flood mode by using the hydrological data of Dafen river basin in Jiangxi province. On this basis，the water level prediction methods based on average rainfall and point-by-point rainfall are proposed respectively to carry out the actual data prediction analysis. It is an exploratory research in the field of data hydrology，which has both important theoretical value and practical significance.