Abstract: In this paper,the authors intend to make use of the Cutout Aggregation Classification Method of Fuzzy Mathematic for the purpose of studying the Classification of Picea neoveitehii Formation distributing over Xinglong Mountain some forty five kilometers from Lanzhou.Four associations have been divided.There are Picea neoveitehii-Sinarundinaria nitida-Carex sp.Association,P.neoveitehii-Sinarundinaria nitida Assoc.,P.neoveitehii-Carex sp. Assoc.and P.neoveitehii-Shrubs Assoc.The result of such a study shows that it is a simple and exact method to apply the Fuzzy Mathematic in classifying the communities of forest especially to the division of the lower units of classification.The authors consider that such a method can be extended generally in the classification of forest communities below the unit of Formation.Methods of classification of units above Formation have been also discussed in this paper.