Picea crassifolia, a major constructive and dominant species in the subalpine montane forests of the Qilian Mountains, plays a vital role in preserving soil and water, regulating regional climate and maintaining ecological balance. Exploring the dynamics of plant population can reflect the current status of the population and its potential driving mechanisms, which helps to predict future population dynamics and provides a scientific basis for the conservation and restoration of the forest ecosystems in the Qilian Mountains. However, despite extensive research on this species, little is known about its population dynamics. To fill this gap, this study was conducted to reveal the population dynamics of P. crassifolia based on the community structure data from 10.2 hm² P. crassifolia dynamic monitoring plots. Specifically, we analyzed the population characteristics of P. crassifolia by preparing static life tables, plotting trail-level structure, survival curves, mortality curves, disappearance rate curves, and four survival analysis function curves. Notably, the diameter class structure rather than the age structure was used in this analysis. Moreover, the population dynamics trends were predicted by the population dynamics change index and time series model. The results showed that:(1) The age structure of the P. crassifolia population was roughly inverted J-shaped, with abundant seedlings and small trees reserves. (2) The survival curve of the population tended to be similar to the Deevey-II type, indicating that the population was a stable one, and the trends of mortality and disappearance rate curves were basically the same, both reaching the maximum at the second and eighth age classes. (3) The survival rate curve showed a significant downward trend; the cumulative mortality curve showed a significant upward trend; the mortality density curve decreased slowly, while the hazard rate curve showed an overall upward trend. Therefore, the growth of the population was characterized by a rapid decline in the early stage, stabilization in the middle stage, and decline in the later stage. (4) The dynamic index of population changes V_pi>0 indicating that the population was growing, V_pi'>0 and it is close to 0, indicating that the population tended to be stable. (5) The time series prediction analysis showed a stable population growth trend after the next 2, 4, 6, and 8 age classes of time. To conclude, the study shows that the population is a stable growing one and will keep growing gradually in size as long as it does not suffer strong disturbances in the future. The high mortality rate of young individuals early in the renewal process suggests that future management should focus on protecting and improving the growth conditions during the first and second age classes of the plants to improve the survival rate of seedlings and small trees.