Based on the monthly precipitation and temperature data from 40 meteorological stations in Ganjiang basin during 1966—2005, the Standardized Precipitation Evapotranspiration Index (SPEI) at different time scales is used to reflect the status of drought and flood event at different time scales, the temporal-spatial patterns of drought and flood events are analyzed with wavelet analysis and GIS spatial technology. The results show that the drought and flood events above moderate level during the past 40 years occurred 6 and 7 times, respectively. In the evolution process of the drought and flood in the basin, three main periodic changes existed. Verification from wavelet variance suggests that periodic oscillation around 10 years is the most intense, which is the first main cycle of the long term change over Ganjiang basin. Heavy flood events areas are mainly in the southern Ganjiang basin, while the heavy droughts primarily happen in the southwest region. Flood events in summer is the most serious and located in the outlet of the Ganjiang basin near Nanchang and Fengcheng. However, droughts in summer and autumn distribute wider and last longer.