Abstract:Based on the monthly precipitation data of 88 observing stations in Gua ngxi from 1961 to 2006, drought and flood grades in winter and autumn are divide d with the method of Z index, and the annual change and spatial-temporal charact eristics are obtained with EOF. The results show that the overall dry in Guangxi is the main type. There exists a positive correlation between the frequency of flood and drought and the time coefficient. The circulation characteristic at 50 0 hPa in the same season is analyzed. The results show that in flooding autum n, the trough at the eastern part of Ural is deeper, the high pressure in the So uth Sea is stronger and the subtropical high is weaker than in drought autumn. W hile in flooding winter, the high pressure is in North and the low pressure in S outh. The cold air path inclined to the south, and the geo-potential height is l ow at the Tibetan Plateau, which can lead small trough moving eastward and affec ting Guangxi.