Abstract: With EOF,REOF,Mann-Kendall test,Morlet wavelet,Second-order polynomial fitting analysis and composite analysis method,abnormal spatial distribution characteristic,the autumn rainfall distribution of Southwest China has divided into two different areas,temporal evolution rule and the drought-flood characteristics of autumn rainfall in Southwest China are studied in detail by using autumn precipitation data for 72 stations during 1959-2013 and NCEP/NCAR reanalysis data.The results show that there are both common features and individual differences.The mutation of two areas both had occurred in the midterm of 80's in the 20th century.The two areas have the consistency characteristics of six-year cycle and the significant differences in more than 10 years decadal long period.there is an obvious change process for the high side-less than normal period since 1985,a decreasing trend for two regions is difference,but more obvious decreasing trend in South area.autumn precipitation in North area has a upward trend slowly and more obvious annual fluctuation after 2000.The study also shows that the feature of Water Vapor Transport and atmospheric circulation which affect with key area have an obvious difference in two different regions.It shows the drought-flood characteristics of autumn rainfall for North region is related to cold air in north,the circulation system in middle-and-high latitude,water vapor transport in the Bay of Bengal and in the western Pacific area;South region are related to Indian-Myanmar trough,southern trough and water vapor transport in the Bay of Bengal.