关键词: 不平衡数据集, 级联结构, Bagging算法, 接受者操作特性（ROC）曲线

Abstract: Borrowing the idea of cascade structure，this paper proposes a new method to classify imbalance dataset，Bagging classification on the basis of cascade structure.This method eliminates a part of majority class at each cascade node，which can make the dataset go balance step by step，obtains traindata using under-sampling technique，and trains classification by Bagging.Then every classification is ensembled gained at each cascade node to a new classification.Experiments on 10 UCI datasets show that this method excels Bagging and AdaBoost on both recall and F-value.

Key words: imbalance dataset, cascade structure, Bagging, Receiver Operating Characteristic（ROC）