The late rice drought index is constructed from the aspect of crop moisture demands.The drought level index of late rice in Hunan is brought forward through analyzing contradistinctively the drought index and drought data of the typical year.The validation with the drought data of late rice in growing season shows that droughts can be reflected by the late rice drought index and drought level index. The results show: as for growing seasons，the probabilityes of extreme drought in the fast growing，midgrowing，and maturity stages are greater than that in the prime growing season obviously， generally greater than 40%; as for regions， the probabilities of severe drought in the middle and northern parts of Hunan are greater than those in the western and southern parts.This model can be used to analyze the drought situation of late rice in different parts of Hunan Province at different times， providing useful references for drought resisting of late rice.