Sinojackia microcarpa is one of the extremely small populations species in China, it is a level-Ⅱ national key protected plant. To reveal the survival potential and endangered mechanism of the population, and provide the basis for population protection, a sample survey was conducted in the natural concentrated distribution area of S. microcarpa in Jiande City, Zhejiang Province. The structural characteristics of S. microcarpa were studied in space instead of time, the population static life table and population survival curve were drawn, and the population dynamics and time series were used to quantitatively predict the future development trend of the population. The results showed that: (1) The structure of diameter, height and crown structure all indicated that the age structure of the population was generally declining, the young trees had high mortality, while the adaptability of the adult tree to the old tree was enhanced, and the growth situation was stable compared with the previous period. (2) The life curve belonged to the Deevey-Ⅲ type, survival analysis showed that the population of S. microcarpa had a sharp decline in the early stage and the early mortality rate was high. (3) Time series analysis predicted that after 2, 4, 6, and 8 age classes in the future, the number of young individuals of S. microcarpa will decline, and the age structure will be in a decline dynamic where adult trees dominate. (4) The population dynamic index indicated that the overall structure of the population fluctuated greatly, the ability to resist external interference was weak, and the environment had a strong effect on individual selection. In order to promote the natural renewal of the population, in-situ protection measures should be strengthened to reduce the threat of human interference to the individual living environment, it will help increase the conversion rate of seedlings to saplings, and achieve the restoration of population.