Betula platyphylla-Larix olgensis forest is a secondary forest established after volcanic eruptions on the eastern slope of Changbai Mountain and an important stage in the succession series of dark coniferous forest. It is of great significance to clarify the growth and extinction of the dominant populations to reveal the mechanism of succession. Taking the dominant population of B. platyphylla and L. olgensis forest in Changbai Mountain area as the research object, the data obtained from the standard plot survey in 2020. In this study, the age structure and dynamic characteristics of B. platyphylla and L. olgensis populations on the eastern slope of Changbai Mountain were studied by compiling static life tables, plotting survival curves and survival analysis function curves, calculating dynamic indexes, and referring spectral analysis and time series model predictions. The results showed that:1) the diameter class structure of B. platyphylla population presented a typical inverted "J" distribution, and the number of individuals of age class I accounted for 52.6%; The population of L. olgensis showed a rough bell-shaped pattern. 2) The quantitative analysis of population dynamics showed that the dynamic change indexes V'_pi of B. platyphylla population and L. olgensis population were both greater than 0, revealing that both populations were of growth type. But the V'_pi of the latter approached 0, indicating that L. olgensis population was affected by external disturbances. 3) In general, the mortality and disappearance rate curves showed a same trend of B. platyphylla population and L. olgensis population, and the survival curves were Deevey-II. 4) Survival analysis showed that the population of B. platyphylla decreased sharply in the early stage (Ⅰ-Ⅳ) and leveled off in the middle stage (Ⅳ-Ⅶ). The L. olgensis increased in the early stage (I-III), stablilized in the middle stage (III-IIX), and declined in late stage (IX-XIII). 5) Spectrum analysis showed that the fundamental wave of B. platyphylla and L. olgensis population was the largest (1.63 and 0.85), indicating that the natural regeneration of the population was controlled by biological characteristics. 6) The number of individuals for B. platyphylla increased gradually with time, whereas L. olgensis showed an increasing trend as a whole although fluctuation was profound.