Abstract: To address critical research gaps in the ecological characterization of monsoon evergreen broad-leaved forests in southwestern Yunnan, this study conducted a comprehensive analysis of forest community structure within the Nanpenghe Nature Reserve. Thirty survey quadrats (30 m×30 m) were established to assess species composition and analyze community structure using cluster analysis, floristic secondary degree analysis, and the Jaccard similarity index. The investigation yielded the following key results: (1) A total of 678 wild vascular plant species from 128 families and 372 genera were recorded; (2) Four distinct community types were identified through comprehensive analysis of clustering results, community physiognomy, floristic composition, and expert evaluation; (3) The assemblage dominated by Lithocarpus fenestratus (Roxb.) Rehder+L. truncatus Rehd. exhibited the highest anthropogenic disturbance levels and floristic secondary values; (4) Inter-community similarity, quantified by Jaccard similarity indices, ranged from “extremely dissimilar” to “moderately dissimilar”. These findings underscore the ecological significance of evergreen broad-leaved forests as the dominant zonal vegetation in the region, characterized by rich species diversity, complex structural organization, and stable ecosystem development.