Abstract: The flood/drought characteristics of global, northern and southern hemisphere in June-August are investigated by using global land precipitation dataset during the period of 1920-2000.The following two weighted mean indices are used to describe the extent of global flood/drought.(1) The weight ed mean June-August precipitation anomaly index:the June-August precipitation anomaly(the 1920-2000 mean was used) at each grid point was mult iplied with the cosine of the latitude of the grid point, and added together to get a series of 81 years.Normalizing the series yielded the global weighted mean June-August precipitation anomaly index.The larger the index, the more the mean precipitation, thus direct ly reflecting the interannual change of global June-August total rainfall.(2) The weighted mean June-August flood/drought area index:adding all the cosine of the latitude of the grid points of June-August positive precipit ation anomalies yielded a series of 81 years, and normalizing the series got the weighted mean June-August flood/drought area index.The larger the index, the larger the wet area, thus directly reflecting the global June-August mean flood/drought area.There is a higher positive correlation(correlation coefficient= 0.71) between the two global dry/wetindices.The two series indices from 1920-2000(81 years) were sorted descendently according to their values respectively, and then the first 20 years and the last 20 years in the two sorted seried were defined as global flood and drought years respectively.The differences between flood and drought years are examined with Monte Carlo test.The results indicate that 1988(1930) is globally the wettest(driest) year during the period, and the next is 1954(1976).The flood/drought chara-cteristics experienced decadal change:during 1920s global drought in June-August occurred frequently, and from 1920s to 1940s global flood year in June-August occurred infrequently, then flood years were globally observed in the period of 1950s-1960s.In the period from 1970s to 2000 global land flood/drought frequently happened with flood years more than drought ones.The flood/drought characteristics of Northern Hemisphere are agreed with ones of the global.The southern and northern hemisphere are taken as a whole respectively, and no obvious correlation is found between the northern and southern hemispheric June-August flood/drought.However when the warm(cold) event occurs, the drought(flood) may happen in June-August in the southern and northern hemispheres.The global land flood/drought in June-August are highly correlated with the ENSO events.