Abstract: Based on the data of 55 quadrates surveyed in Taibaishan, the peak of Qinling Mountains, the species richness (S), Simpson index (D), Shannon-Wiener index ( H′), Pielou evenness index (Jsw) and Alatalo evenness index (Ea) were measured and their characteristics were studied according to 15 community types classified using DCA and TWlNSPAN. The results are: 1 )The correlation between the altitudes where different communities distributing and the first axe of DCA (X1) was significant and the multiple regression coefficient R2 was larger than 0.9; 2)Between 1500m and 2300m above sea level the species diversity reached the highest level of the whole mountain; 3)When communities succeeds from herbosae generating on the abandoned cropland to the relatively stable forest such as communities dominated by Quercus, the fluctuant characterictics of the species diversity in different communities were in accord with the general dynamics of the successional series.