关键词: 支持向量机（SVM）, 多类分类, 2_a_2方法

Abstract: A new method of 2_a_2 SVM multi-class classification is put forward, the advantage of which is to make good use of the results of each sub-classifier so that the problem of classification of different classes can be resolved only by using the smallest numbers of sub-classifiers.In order to verify the effectiveness of this method，experiments have been made on CMU database，and the experimental results are satisfactory.If this method is applied to resolve the problem of classification of lots of classes，comparing with the current methods，it also has the same advantage.

Key words: Support Vector Machine（SVM）, multi-class classification, 2_a_2 method