It is important to study the reasons and characters for summer drought and flood and its rainfall anomaly distribution in the Changjiang-Huaihe River Basin.By using the NCEP/NCAR reanalysis data and the 1951-1998 summer rainfall data of 160 stations from CMA,the REOF analysis of summer (JJA) precipitation in eastern China was performed,and results show that the distribution of summer rainfall in the middle-lower reaches of Yangtze River can be described by two zonal rain bands:the southern branch band lies to south of the lower reach of Yangtze River,along the Hunan-Jiangxi-Zhejiang area;another locates along the southeast of Chongqing and Shaanxi-Hubei-the south of Henna-Anhui area.Interannual and interdecadal features for both branch bands are obvious with the 14-yr period in the southern branch band and the 8-yr period in the northern branch band.And moreover the both branch bands have different time periods of excessive/deficit rainfall,which is close related with the general circulation,especially the intensities of summer monsoon and subtropical high have significant impacts on both the location and size of their precipitation.