The plant species in Huangshan Mountain (Mt. Huangshan) are abundant. Nevertheless, a comprehensive analysis of the relationship between biodiversity and environmental factors is lacking. This study aimed to analyze how multiple factors affect biodiversity and explain the mechanisms underlying community assembly processes and species maintenance. Thus, we compared the different biodiversities among Evergreen Broadleaf Forest (EBF), Deciduous Broadleaf Forest (DBF), and Mixed Needleleaf and Broadleaf Forest (MNBF) in a total of 75 plots in each community using a non-parametric Wilcoxon rank-sum test. Then, we employed Mantel tests to quantify the influence of ecological conditions, including spatial predictors, topographical variables, soil composition, and climate factors, on the three forest communities. Our findings revealed the following: (1) The species diversity and phylogenetic diversity within the EBF and MNBF were found to be higher than that in the DBF. The functional richness (FRic) in the MNBF was higher compared to the other two communities, whereas the functional evenness (FEiv), functional divergence (FDiv), and functional dispersion (FDis) in the DBF were the highest. (2) The species diversity of different canopy plants was positively correlated with phylogenetic diversity and functional richness, yet negatively correlated with FEve, FDis, and FDiv. Phylogenetic diversity exhibited a negative correlation with functional diversity for both total and shrub layers, whereas it showed a positive correlation with functional diversity for the tree layer. The type of forest canopy exhibited the strongest correlation with functional diversity. (3) In the redundancy analysis, environmental factors had a stronger influence on biodiversity than spatial distance, indicating that deterministic processes had a greater impact than random processes. The findings underscore the importance of key factors that are often overlooked in the work of protecting Mt. Huangshan, such as elevation, aspect, total phosphorus (TP), and precipitation of the driest month (Bio.14) etc. This provides theoretical guidance for the ecological restoration of forest vegetation in Mt. Huangshan.