Abstract: The climatic characters of August low temperature of Yunnan are analysed by using the temperature data 1951 to 1996. The results show that the chilling damage in Yunnan in summer is not only the chilling damage of the obstacle type. There have been five low temperature years in Yunnan in recent 45 years. They are different from the five low temperature years that occured in the northeastern China and August lowt emperature years, occur mainly in years with lower temperature.