Extreme meteorological and hydrological events may cause major disasters and heavy social and economic losses. Therefore, more and more studies have focused on extreme hydro-meteorological events in various climates and geographic regions. Based on nearly 50 years of observed records of the Poyang Lake Basin, the occurrence and changing trends of extreme streamflow indices, including the annual maximum flow, annual peak-over-threshold flows, and low flows, were analyzed for ten hydrological stations. The results indicate that most annual maximum flows occurred from April to July, highly attributed to the Southeast Asian summer monsoons, whereas the annual minimum flows were concentrated between January and February. As for the low flow indices (the annual minimum flow, annual minimum 7-d flow, and annual minimum 30-d flow), a significant increasing trend was detected in most parts of the Poyang Lake Basin. The trends illustrate the potential effects of climate change and human activities on the hydrological cycle over the Poyang Lake Basin.