Abstract: The reservoirs in the Upper Yangtze River are refilled in August-October. This period is in the late rainy season. If a reservoir cannot be refilled at a certain water level before the end of the rainy season when precipitation is concentrated, it will seriously affect the benefits of the reservoir. To optimize the existing reservoir impoundment operation policies, this paper selects the Rainy And Dry Season (RADS) data set of Texas A&M University, and analyzes the characteristics of the rainy season in the Upper Yangtze River. The results show that the characteristics of rainy season for China and the Upper Yangtze River revealed by RADS are similar with those from the existing researches. Thus the data set is applicable in the study area. The demise dates of rainy season in the Wu River Basin fluctuate obviously calling for the medium- and long-term hydrological and meteorological forecast of the Wu River Basin for the warning of the earlier end of the rainy season. For the regulated September 1st and October 1st of reservoirs initial impoundment time in Wu and Min-Dadu Rivers, there were situations that the rainy season ended earlier during 1961-2007. Namely, for reservoirs in the two basins, considering flood prevention tasks and forecasted streamflow conditions, it is necessary to consider further advances the initial impoundment time.