Abstract: A systematic investigation was conducted of the species composition, diversity, and environmental factors across the tree, shrub, and herb layers of 32 plots within the Quercus aliena var. acuteserrata community on the southern slope of the Funiu Mountains. The influence of environmental factors on species diversity was analyzed using Redundancy Analysis (RDA). The results showed a total of 146 plant species were recorded across the 32 plots. The tree layer had the fewest species (33), with Q. aliena var. acuteserrata dominating overwhelmingly (importance value: 210.74%). The shrub layer had the most species (74), including 29 tree seedlings, while the herb layer had 64 species but exhibited significantly retarded development, with an average herb cover of only 1.74%. Significant differences in diversity indices among layers, ranked as: overall diversity > shrub layer > herb layer > tree layer. Environmental drivers showed distinct layer-specific effects. Higher elevations and greater soil total potassium enhanced overall community diversity. Tree species richness was favored by higher elevations, abundant soil potassium, thicker litter layers, acidic soils, and lower phosphorus availability. Shrub diversity increased with elevation, while herb diversity correlated with higher soil total phosphorus. The driving mechanisms of species diversity vary across different layers in the Q. aliena var. acuteserrata community in the southern foothills of the Funiu Mountains. Therefore, biodiversity conservation and management strategies should fully account for the feedback mechanisms of species across these different layers.