Abstract: The plant species loss, dynamics of tree population as well as speccies compostion were enumer-ated based on the comparative researches of floristic composition, physiognomy and plant diversity on a frag-ment of tropical rain forest isolated more than 30 years in a Dai's holy hill in Xishungbanna, south Yunnan. In 1958 - 1959, 246 native seed plant species in 196 genera of 80 families were recorded in the fragment. By this study, 55 species in 53 genera of 7 families have not been recorded in the inventory. Among these possibly lost 55 species, 18 are climax tree species of the tropical rain forest, 30 are shade - tolerant under-storey species, 2 are heliophilic specis and 5 are indifferent species.

Key words: Isoland fragment of tropical rain forest