Based on seed plants in Flora of Enshi, combining with field investigation statistics in natural reserves, we studied the species diversity, composition of genera, families and floristic components in Southwest of Hubei. Results showed that: (1) there were 3 053 seed plant species in Southwest of Hubei, belonging to 1 008 genera and 164 families, which accounted for 74.79% species of Hubei, 11.20% of China. Among them there were 9 families, 28 genera, and 45 species in Gymnosperm, and 155 families, 980 genera, and 3 008 species in Angiosperm. In addition, there were 1 576 herbplants in total, which showed multiple life forms, abundant herb species, more perennial, deciduous species, various rare and endangered plants and high biodiversity in studied area. (2) Rosaceae (210 species), Compositae (198 species), Liliaceae (131 species), Gramineae (126 species) and Leguminosae (111 species) contained more species than other families in Southwest of Hubei. Among characteristic families, Betulaceae had the highest importance value （22.00）. Genera and species tend to concentrate in limited number of families, large families and genera possessed obvious superiority. The monotypic or oligotypic families and genera were much abundant. (3) The natural flora of seed plants in Southwest of Hubei were divided into 11 arealtypes and 14 variations in families. The tropical elements took 65.25% (77 families), 38 families (32.20%) were temperate ones, and 2 families were endemic to China (1.69%), tropic distribution compositions hold a dominant position. Genera were divided into 15 arealtypes and 23 variations. 41.06% (388 genera) of total genera were tropic composition, 51.32% (485 genera) were temperate composition, and 6.03% (57 genera) were endemic to China. Species were divided into 15 arealtypes. The temperate elements took 59.70% (1 572 species), 934 species (35.47%) were tropical ones. 110 species were endemic to China (4.18%). Arealtypes in genera and species were dominated by temperate element. Based on this study, the flora of Southwest of Hubei were of characteristics with transition of tropical and temperate zone. The flora was ancient, and geographical components were complex.