Based on 531-yr(1470-2000) drought/flood level data of 38 stations in eastern China,the EOF analysis is used to achieve three primary drought/flood types:Huanghe-Changjiang homogeneous anomaly pattern(Pattern Ⅰ),Huanghe-Changjiang contrary anomaly pattern(Pattern Ⅱ),and Huanghe-Jianghuai-South China alternate anomaly pattern(Pattern Ⅲ).Then six summer drought/flood patterns in eastern China are defined according to the positive and negative phases of above three patterns.In view of the instance that a single index can not depict the drought/flood anomaly distribution accurately,this paper utilizes combined three-index to compartmentalize annual drought/flood pattern in term of the most noticeable feature,and then presents a new table of 531-yr summer drought/flood pattern in eastern China.Finally,a comparison is made between the decadal frequencies of six drought/flood patterns and the EOF time coefficients,showing that they have preferably coherence,which verifies that,to a certain extent,compartmentalization is reasonable on the whole.