Abstract:Based on the theories of Tree and Spanning Tree in Graph theory, this paper selects the data of the distribution of 8 species belonging to the genus Cephalotaxus in China. By means of Graph theoretical methods of classification (that is to say Prim‘s method in detail), the quantitative study is carried out for the distribution of 8 species belonging to the glenus Cephalotaxus in China. The result shows that this paper is basically successful for the application of Graph theoretical method of classification in the division of the floristic elements of Ce-phalotaxus in China, and the results of this method and the classical analysis are basically unform, especially using the asymmetric information coefficients to con-stitute dissimilarity matrix.