By using the conventional meteorological data of 125 stations and dividing 5 dur ations from 1959 to 2005, the drought risk assessment in Yunnan Province was con ducted with the fuzzy information theory and overlimit probability principle. The establishment of synthetic drought index was mainly based on the Thornthwait e drought index and supplemented by selfdefined effective precipitation index. The results showed as follows: the most drought risk period is in January to Ma rch every year; the probability of drought in most area is 60%～100%; the heavy drought probability is 20%～60% with some area of 90%. The drought risk in Nove mber to December is in the second place. The drought probability in most area is 30% ～60%; the heavy drought probability is 20%～60%. There is mostly no drought ris k in June to August. The drought probability is less than 5% in September to Oct ober and there is no heavy drought at all. The drought probability is 10%～20% i n April to the first ten days of June in about half area of Yunnan, 20%～40% in the area of 29%, 40%～80% in the area of 21% and the heavy drought risk is less than 5%.