The vegetation data of the evergreen broad-leaved forest in Gutian Mountain Nature Reserve are used as the information for analyses of flora and species diversity. There are 64 families, 114 genera and 198 species, including 7 families, 8 genera and 19 species of peridophyte, 2 families, 2 genera and 2 species of gymnosperme, 55 families, 104 genera and 177 species of angiospermae. The floristicelements are complex, and the total of tropical distribution type amounts to 50.94 %. The species diversity of different communities are different, it of Castanopsis forgesii forest numbers first, and it of Castanopsis eyrei- Schima superba forest is the smallest. In the vertical structure of community, the species diversity is the highest on shrub layer, and decreases from shrub, tree layer to herb layer. The species diversity index between the tree layer and the shrub layer has no significant difference, the species richness and species diversity index of the tree and shrub layer are obviously bigger than those of the herb layer.