Abstract: Ganshiling is situated at the southern part of Hainan Island, at 109°34'-109°42'E. and 18°21'-18°26'N., with an altitude of 10-347m. The an-nual average temperature and rainfall are 24.5℃ and 1200mm. respectively, the solar radiation energy is up to 134. 1 Kcal./cm² annually. The regionalvegetation is tropical rain forest. There are 1144 species of vascular plants belonging to 171 families and679 genera in the studied area, of which 28 families, 62 genera and 93 spec-ies are Pteridophyta;3 families, 4 genera and 4 species are Gymnosper-mae;140 families, 613 genera and 1047 species are Angiospermae. The main families of the flora are Annonaceae, Myrtaceae, Sterculi-aceae) Euphorbiaceae, Moraceae, Rutaceae, Sapindaceae, Rubiaceae, Zin-giberaceae, Dipterocarpaceae, Dilleniaceae, Ochnaceae etc., most of themare tropical distribution. According to the geographical distribution of spermatophytic genera inGanshiling, They may be divided into 13 types and 8 sub-types, of whichPantropic and Trop Asia elements are two largest parts of the flora. At specific level, the Trop. Asia elements has highest percentage (54.14%).They can be integrated into the following categories:Distribution type No. of genera% No. of species% Cosmopolitan 30-22-Tropical 554 94.4 757 73.57 Temperate 29 4.9 11 1.07 Tethysian (Ancient 1 0.2-Mediterranean) Endemic to China 3 0.5 261 25.36 Total 617 100 1051 100 Endemism is relatively poor, with 3 genera and 261 species of endemicto China, 135 species endemic to Hainan, most of them are the dominantspecies in their communities. Comparing the composition of the flora with those of 7 neighbouringregions, the flora of Ganshiling is quite similar to those of Indo-Chinapeninsula and Java. The indices of generic similarity are 88.07% and 85.86%respectively. We consider the flora of Ganshiling represents some floristic charac-teristics of the tropical rain forest in our country. The investigation onthe flora is helpful for us to understand the floras of Hainan and China.

Key words: Ganshiling, S.Hainan, Flora