The population quantity and distribution pattern of Changiostyrax raxdolichocarpa in Hupingshan and Sangzhi, Hunan province, were investigated and analyzed. Age structure analysis showed the population of Changiostyrax raxdolichocarpa was a declining one, in which there were mainly small trees (IV age group) with infant and old trees lacked. Before entering the physiological age of death, there were 2 mortality peaks of Changiostyrax raxdolichocarpa, one of the which was in the young trees stage (II, III age groups) caused by intraspecific and interspecific competition (mainly for light) and the other was in the stage of the trees growing into big ones (V, VI age groups). Besides, shallow soil, lodging of big trees and man-made cutting intensified the peaks. The whole population presented a gathering distribution, in which sapling trees distributed in a gathering way and big ones in a random way. Through investigation we found that the reasons causing Changiostyrax raxdolichocarpa endangered were low seed germination rate, less competitiveness and Man-made interference etc.