Abstract:Some basic characteristics of tropical mountain rain forest communities with emphasis only on tree layer of primary and regenerated stands in Jianfengling, Hainan Island, were studied since 1983. The results indicated that the forest communities showed rich floristic composition, and high diversity index being up to 5.8-6.3 for 2 primary stands and 4.5-4.8 for 3 regenerated stands as calculated by the Shannon-Wiener diversity index.Over 8O% of the total genera in the conununities were of tropical components. The diameter at breast height and tree height classes showed a reasonable distribution in the primary and regenerated stands. Based on the results of frequency measurement, the frequency va1ues of most tree populations (more than 8o% of the totals) were less than O.2 in the communities,and the frequency distribution showed the special pattern that was different from the Raunkiaer‘s Frequency Law.