Abstract:By using daily precipitation and temperature data in 170 meteorological stations and historical drought disaster information in the Huaihe River Basin from 1961 to 2010, this paper studies the adaptability of the CI index, and then analyzes the spatial temporal characteristics of drought in the recent 50 years with a variety of statistical methods. The results show that the correlation coefficient between drought days calculated by CI index and drought disasters has past the 0.01 significance level test, indicating that the CI index has good regional adaptability in the Huaihe River Basin. The spatial distribution of the average drought days which descends from north to south is latitudinal. The trend of drought days ascends in the east and west, and descends in the central and north of the basin, but they all have not passed the 0.05 significance level test. The cumulative percent variance of the EOF first three modes reaches 94.4%, the first distribution pattern is consistent within the whole basin, the second is contrary between south and north, and the third is contrary between east and west. The drought days have experienced four circulations since 1961, and now are in the period less than normal. The Mann Kendall mutation test shows that there is no obvious mutation point of drought days in the Huaihe River Basin in the recent 50 years.