Abstract: In this study, we analyzed the species composition, floristic composition, community structure, and classification of Castanopsis forests in Hubei Province, China, based on a comprehensive survey. Results showed that: (1) There were 376 species of vascular plant in 210 genera and 88 families, including 73 species of evergreen and 48 species of deciduous trees. Thus, Castanopsis forests were typical evergreen broad-leaved forests dominated by evergreen tree species. (2) There were more tropical components than temperate components. In terms of the floristic composition of the genera, tropical composition was roughly equivalent to that of temperate composition. (3) There were significant longitudinal and altitudinal gradients in biodiversity, but no significant latitudinal patterns. Soil had very limited impact on biodiversity patterns. (4) Castanopsis forests in Hubei could be classified into five main alliance types: Castanopsis tibetana Hance Forest Alliance, Castanopsis sclerophylla (Lindl.) Schott Forest Alliance, Castanopsis fargesii Franch Forest Alliance, Castanopsis faberi Hance Forest Alliance and Castanopsis eyrei (Champ.) Tutch. Forest Alliance. Canonical correspondence analysis showed that among the environmental factors, altitude, longitude, slope, and soil total phosphorus had the greatest influence on species composition. Variance decomposition analysis indicated that the topographical and soil parameters had significant influence on species composition of Castanopsis forests, with an interpretation rate of 68.94%. (5) The diameter at breast height distribution of trees in all Castanopsis alliances showed a single peak to the left. The species-abundance distributions were typical inverted “J” curves, with a few common species and many rare species. In all, our results showed that species diversity in Castanopsis forests in Hubei was rich, with a high tropical composition, and the forest could be classified into five alliances. This study provides theoretical and data support for the protection and management of evergreen broad-leaved forests in Hubei.