Abstract: Based on the theory of the grey system, this paper selects the data of the appraising eharaeter of the 20 specimens for distinguishing P.villosa from P.parvifolia. By means of the method of the grey clustering analyses, the quantitative cluster is carried out for P.villosa, P.parvifolia and its variety. The result shows that the counting cluster and the morphological cluster show no difference, and the former one is easy to count and practise so that it provides a new method for systematic botany.