Abstract: Autumn Low Temperature （ALT） is low temperature weather processes which daily average temperature during September less than or equal to 20℃ and continues more than three days， meanwhile it is main agricultural meteorological disasters which affect the double season late rice production in Hunan province. Based on daily temperature data from meteorological stations in Hunan during 1961-2013， the climate changing characteristics of beginning date of ALT in different regions of Hunan were analyzed， and predict model of beginning date of ALT was built by using the mean generating function based on the time series of beginning date of ALT from 1961 to 2010. The results showed that beginning date of ALT in different regions presents significant interdecadal variation during last 53 years. Average beginning date of ALT appears in later period of late September. The earliest time of northern and central Hunan appears in the beginning of early September， and which of southern Hunan appears in the late of early September. The latest time of northern Hunan appears in the early stage of the middle of October， and which of southern and central Hunan appears in the late of middle October. Frequency of occurrence of ALT which affects the double crop late rice production in southern Hunan met twice in three years， which in central Hunan met once in two years and in southern Hunan met twice in five years. The results of predict model of beginning date of ALT which had been built by using the mean generating function showed that the historical fitting rate was 92% in northern and central Hunan and which was 94% in southern Hunan. The predict results during 2011 to 2014 showed that the mean generating function model has strong predictive ability for beginning date of Autumn Low Temperature in Hunan．

Key words: Late rice in Hunan, Heading and flowering period, Autumn low temperature, Climate changing, Mean generating function, Predict