Abstract:Based on extended Lance and Williams' model, two polythetic agglomerative dustering strategies, i.e. the Average distance of new cluster and the Weighted average distance,are introduced in this paper. As an example, vegetation data of shrub, Vitex negundo var.heterophylla, collected from Zhongtiao mountains in Shanxi Province were analysed with these two new methods. The Results illustrate that the two methods are effective and successful in describing the relationships between vegetation clusters. They have some advantages compared with fuzzy equivalence clustering and group averaging, and are partically suitable for vegetation classfication at association level.