Using data of summer temperature and precipitation in recent 50 years of Anhui Province,the climate change in summer season is analyzed and the inevitability of extreme climate events is explained. The results indicate that (1) Summer temperature decreased and precipitation increased in recent 50 years,so temperature is in a phase of low climate base state now and precipitation in high. (2) Climate variability also vary with time,and now both temperature and precipitation are in a phase of high climate variability so that we should be aware of frequent occurrence of extreme climate events such as flood,high temperature. (3) Maximum entropy spectrum analysis shows that the summer precipitation varies periodically for 2- to 3-year,with the character of QBO.