The sequential clustering method is an effective way to diagnosejump points in hydrologic research. However, the method only considers smaller deviations between the same classes, but ignores the larger deviations between different classes. For that reason, this paper proposedthe improved sequential clusteringmethod considering both smaller deviations between same classes and larger deviations between different classes. The improved sequential clustering methodhas been applied to identify jump points ofsome average annual flow seriesand comparedwith traditional sequential clustering method. The results show that theimproved sequential clusteringmethod is clear and effective to identify jump points.