Wuyi Mountains preserve the primary forest ecosystem characteristic of the mid-subtropics. We established a large-scale plots in this area according to standard international protocols (Center for Tropical Forest Science, CTFS). Community characteristics such as flora composition, floristic characteristics, DBH structure and spatial distribution patterns in a 9.6 ha plot were analyzed. The results showed that the vascular plants in the plot belonged to 68 families, 135 genera, 232 species. Among these plants, trees (DBH ≥ 1 cm) belonged to 44 families, 86 genera, 171 species. For plants with tropical elements, family and genera accounted for 68.58% and 58.83% of total, respectively, which indicates a tropical feature of the ecosystem. There were many rare and endangered species, including four State Priority Protected Wild Plant Species at Level II, two threatened species (VU) of Red List of China’s Biodiversity, one species of Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES ) (Appendix II) and 72 endemic species to China. Rare species (N = 29, less than 1 individuals/ha) accounted for 16.96%. Fagaceae and Theaceae, with a total importance values of greater than 40%, were most dominant. Castanopsis carlesii, C. fordii, C. eyrei and Engelhardtia fenzlii had the largest importance values but no species significantly dominated the community. Small sized trees dominated the plot, with a mean DBH of 5.10 cm and the DBH-class distribution presented an inverse “J” shape. The emergent layer was divided into two sub-layers with C. carlesii, C. fordii, C. eyrei dominating the first sub-layer. Castanopsis carlesii and C. fordii had an even distribution, at the same time, C. eyrei, E. fenzlii, Syzygium buxifolium and Schima superba had a clustered distribution.