First, the synthetic analysis is conducted on 8 disaster indexes of 36 serious disaster-stricken counties and cities in Wenchuan earthquake by principal component analysis of SPSS software. It is gained that the three principal components and scores of cumulative contribution rate of 83.403%.Then, it is classified about 36 serious disaster-stricken counties and cities by cluster analysis based on the scores of three principal component. The classification result is more Comprehensive, rational and scientific.