Based on the southwest direction of 20 plots in the Dabashan National Nature Reserve, we used hierarchical cluster analysis, species importance values, species richness, intensity of flora differentiation and α, β diversity index to study the distribution of vascular plant species diversity in Reserve along the altitudinal gradient. The results showed that: (1) there were 335 species vascular plants in the 20 studied plots, which belonged to 97 families and 226 genera. The total number of plant families, genera, and species increased first and then decreased with altitude. (2) Plant communities differed significantly in vertical gradients. Comprehensive community growth and hierarchical clustering analysis results showed that the forest communities could be classified into four types, including those the vertical vegetation spectrum was evergreen broadleaved forest and warm coniferous and deciduous mixed forest (below 1 000 m a.s.l.), mixed deciduous and evergreen broadleaved forest (1 000-1 600 m a.s.l.), warm and humid coniferous and deciduous mixed forest (1 600-2 100 m a.s.l.), and subalpine coniferous forest (above 2 100 m a.s.l.). (3) The α diversity index changed vertically. Simpson and Pielou indexes varied less with altitude, The ShannonWiener index of tree layer changed more obviously with the altitude gradient, and decreased with elevation. Mixed forest types had relatively higher α diversity and more intensive flora differentiation than the other types. (4) The β diversity index fluctuated considerably in the low altitude section, the change in Cody index pattern showed a gradual trend of tree layerthe heterogeneity of species between adjacent communities gradually decreased, the species turnover rate decreased and eventually reach to a relatively stable state.