Abstract: The geographical distribution and natural habitats, as well as the population size and the age structure of the population of Keteleeria evelyniana var. pendula in Huaning County, Yunnan Province were studied in this paper, and the biological characteristics, such as the morphological features, the development rule of the growth and its spreading and germination of seeds were well knew. It was concluded that K.evelyniana var. pendula was mainly distributed in the mountain areas near villages, such as Pingdi and Mada in Huaning County; the existing groups of this variety were the small populations, the clustering populations were characterized by the illogical age structure, and the populations were in a relatively unsteady stage. Although the characteristics of the seed wing were good for spreading over long distances, the seed yield was extremely low and the transformation of seeds to seedling is difficult. Therefore, the sexual reproduction was suffocated and the life history tended to break, which is an important one of the internal reasons that results in its being endangered condition at last. Furthermore, the survival of this species is severely threatened by the natural habitats being seriously damaged and the adults being excessively excavated, which is the main external reasons that cause the dramatical decreasing of the individuals in the wild population. The effective measures of protection and utilization were proposed, based on the endangered mechanism of K.evelyniana var. pendula.

Key words: endangered mechanism, Keteleeria evelyniana var. pendula, rare plant