中文摘要：

确定分类数成为聚类分析中的主要问题之一．针对该问题，文章提出了一种新的聚类分析方法即自然聚类法．首先，给出了一个新的类的定义．按该定义聚类，类和类的个数是确定的．相应地，设计了自然聚类的算法．最后通过模拟研究和两个实例分析了所提出方法的有效性．

英文摘要：

How to determine the number of clusters is one of the critical problems in cluster analysis. To solve this problem, a new method of cluster analysis, natural clustering, is presented. Firstly, the clusters and the number of clusters can be obtained easily by introducing a new definition of cluster. Secondly, the natural clustering algorithm according to the definition is designed. Finally, simulation studies and two examples are constructed to illustrate the effectiveness of the proposed method.