Populus wulianensis, a wild plant species with extremely small population, is endangered and endemic in Shandong Province, China. In this study, the structural characteristics of P. wulianensis population distributed in Kunyu Mountain National Nature Reserve was investigated by establishing a static life table and drawing population survival curves. Four survival functions, number dynamic index, and the spectral analysis were used to describe survival status, population dynamics and the periodicity and structural volatility of the population-age-structure replacement process of P. wulianensis, respectively. The results are as follows. Firstly, the age-class structure of P. wulianensis population was a pyramid type with a very wide base and a narrow top. Its population survival curve appeared as Deevey-Ⅲ type. The number of young individuals was abundant but the survival rate was at an extremely low level. The population growth rate was very low. Secondly, the tendency of mortality and vanish curves was decrease-increase-decrease-increase, which showed the mortality rate of P. wulianensis population was the highest at age class Ⅰ. Thirdly, its survival analysis revealed that P. wulianensis population was at an extremely low viability level in the whole life cycle with the characteristics of a sharp decrease in the early stage and decline in the middle and late stages. Fourthly, although population dynamic index suggested that the population was increasing, its population stability was poor and the anti-interference ability was weak. Fifthly, spectral analysis demonstrated that the population was not only affected by the fundamental wave but also significantly affected by some separated small periodic fluctuations. Reproduction strategy, limited space and resource conditions are the major factors limited the growth of P. wulianensis population. Given these, in situ conservation should be introduced and seedlings importation is also recommended so as to avoid the population from decreasing resistance and genetic diversity due to asexual reproduction after multiple generations.