We established experimental plots in representative areas in the Funiu Mountain nature reserve. We investigated plant communities in these plots to discern the pattern of species diversity distribution along the altitudinal gradient. We calculated α-diversity, β-diversity, and γ-diversity using the data thus collected. Alpha diversity of the tree layer peaks in the deciduous broadleaved mixed forest zone at mid-elevation, alpha diversity of the shrub layer increases gradually along the altitudinal gradient, while alpha diversity of the herb layer peaks in low altitude secondary forests and the mountaintop elfin forest. Beta diversity peaks twice, first at mid-elevations where the composition of edificatory species changes, then in areas near the mountaintop. Gamma diversity decreases along the altitudinal gradient. The highest species richness levels occur in areas below 700m and the mid-elevation deciduous broadleaved mixed forest. As elevation rises, Quercus variabilis forest gradually gives way to Quercus aliena var. acuteserrata forest, forming a mixed forest at mid-elevations; dispersed among the edificatory trees are Quercus glandulifera var. brevipetiolata and Quercus aliena, secondary edificatory species that are dominant in some niches. The transition zone is characterized by relatively high levels of species diversity and species turn-over rate. Overall species richness is negatively correlated with altitude.