Knowledge of the spatio-temporal variability of drought characteristics in the entering lake watershed is crucial for water regulation and ecological environment improvement of downstream freshwater lake in the upper and middle Yellow River. In this study, daily precipitation data collected at 23 stations in the eastern watersheds of Wuliangsuhai Lake from 1986 to 2015 were used to analyze the drought characteristics and its variation trends during past 30 years which were described by drought duration and drought severity in terms of Standardized Precipitation Index (SPI) after pre-whitening treatments using the Mann-Kendall test. The results showed that, the precipitation in the mountain area was larger than that in the plain area. The variations of drought duration and drought severity over time were both non-significant, but the drought in the northern and southeastern watershed increased continuously. The short time-scale meteorological drought mainly occured in the central and southeastern parts of watershed, while the medium and the long time-scale hydrological droughts primarily occurred in the northern parts of watershed. Under the condition of slight decrease in precipitation of Wuliangsuhai Lake, the discharge from watershed to lake presented obvious decreasing trend with the influences of the human activities such as hydraulic engineering construction in the eastern watershed. In order to improve lake water quality and control the yellow algae growth, the water supplement from the Yellow River during ice flood season and irrigation clearance period are required to increase in order. Therefore, the balance between the diversion water from Yellow River and the discharge from eastern watershed and reasonable regulation will provide new ideas for the regional lake environment improvement from both the quantitative and qualitative respects.