The instantaneous unit line method has been widely used in Jiangxi province.In order to use the method more rationally in the area for the design of water conservancy projects，27 hydrographic stations with rain collection areas greater than 50 km2and less than 1，000 km2were selected as representative stations.By comparing and analyzing the design flood of the instantaneous unit line method and the objective estimate line method of each representative station，studied and analyzed the application of the instantaneous unit line method in Jiangxi province.In this paper，it is proposed that the factors of scale，importance and geographical location should be considered in engineering design.The results provide a basis for the application of instantaneous unit line method in Jiangxi province.