Abstract: In this paper,the climatic characteristics of the precipitation during the Apr. -Jun. rainy season from 1951-1986 in South China are analysed. There are significant quasi-3-year periodic variations in the precipitation for the Apr. Jun. rainy seasons in South China. Substantial variations are found in the interannual variations in the 1950's. There are anomalously less rainfall in the 1960's and 1980's and anomalously more rainfall in the 1970's. Floods are frequently resulted from the seasonal precipitation, averaging at one instance per 2.6 years and being twice as likely as droughts in terms of occurrence. The EOF method is used to study the temporal and spatial distribution of precipitation for the rainy season and the results show that there are 4 typical precipitation patterns.