Abstract: In order to know about the endangered reason of the reproductive characters in Manglietia hebecarpa C.Y.Wu et Law,a CR species(IUCN),only distributed in Yunnan Province,we studied the sterile pollen,pollen-ovule ratio and seed setting rate of this species by paraffin section and microscopic observation techniques.The random samples were taken from its natural population in Pingbian county in Yunnan province.We found that the pollen abortion reaches 29%,normal pollen-ovule ratio are greater than 4527,seed setting ratio of follicle is 44% and 34% of aggregate fruit.The mating system was obligate outbreeding type according to pollen-ovule ratio and the seed-setting ratio was not high compared with the other species and is not straightly related with pollen abortion.With field survey and analysis,we found the plant natural population was very small and segregative,and we thought the selective abortion of androecium or gynoecium was one kind of reproductive adaption for the external environment stress to some extent in Manglitia hebecarpa.