This paper deals with the Hainan endemic species and genera and their distribution. There are 19 China endemic genera of flowering plants in the island, 8 of which are endemic to Hainan, viz. Pyrenocarpa, Chunia, Setiacis, Parapyrenaria, Wenchengia,Metapetrocosmea, Pentastelma and Cathayanthe. The seed plants of this island amount to 3315 species, of which 1110 species are endearic to China and 505 species or 15.23% of the total species being endemic to Hainan. Most of them occur at altitudes of 300─1400m and some species appear only in limestone area. The flora of Hainan indicates closer relationships to that of Guangdong, Guangxi and Yunnan than to that of E. China and C.China. Many China endemic species in Hainan are in common with those in Guangdong,Guangxi and Yunnan, but not in E. China and C. China. Some species, such as Casearia aequilaterais, Homalium paniculiflorum, Ardisia humilis, Diospyros strigosa, Pseuderanthemum haikangense, Munronia heterotricha and Artabotrys pilosua, occur only in Hainan and S.Guangdong. Those, such as Horsfieldia hainanensis, Munronia hainanensis, Cnesmone anisosepala, Goniothalamus chinensis, Hainania trichosperma, Oncodostigma hainanense, Firmiana pulcherrima and Aristolochia hainanensis are found only in Hainan and S. Guangxi, while Goniothalamus howii, Ziziphus fungii, Begonia anaustinei, angustinei, Schefflera Hainanensis and Symplocos lancilimba only recorded from Hainan and S. Yunnan. Such distribution patterns may beascribed to the relatively identical climate and geological history of Hainan, Guangdong,Ouangxi and Yunnan.