By use of different precipitation data collected by 27 weather stations from 1979?2015 in Dongting Lake basin, we used precipitation Z–index, wavelet analysis and linear trend analysis to do comparative analysis with a set of worldwide available data. The data included observation precipitation(CMD), and the gridded precipitation data including National Center for Environmental Prediction Climate Forecast System Reanalysis(CFSR), European Center for Medium Range Weather Forecasts ERA–Interim reanalysis data(ERA–Interim), the Climate Prediction Center Merged Analysis of Precipitation(CMAP), the Global Precipitation Climatology Project monthly precipitation analysis(GPCP), University of East Anglia Climatic Research unit time–series of high resolution gridded data of month–by–month variation in climate(CRU), NOAA’s Precipitation Reconstruction over Land(PREC/L). It showed that the annual fluctuation in drought and flood was obvious over Dongting Lake basin. In general, the drought and flood grades from GPCP were consistent with that of CMD. There existed a drought trend in Dongting Lake basin, and the trend from ERA–Interim data agreed better with CMD than other gridded data. Quasi–periodic variation of drought/flood were about 18 a, 3 a and 5 a. For all gridded data, variation period of drought/flood from GPCP was close to CMD’s. The frequency and trend of drought/flood varied over different regions in Dongting Lake basin. In gridded data, only the frequency and trend of drought/flood in some regions were same with that from CMD’s. In conclusion, GPCP revealed the characteristics of drought and flood in the Dongting Lake basin in a better way than other gridded data.