The spatial distribution pattern of plant community refers to the individual distribution and configuration in the horizontal space and reflects its survival strategy and adaptation mechanism to the environment. Taking Abies georgei var. smithii forest in Sejila Mountain as the research object, a fixed plot of 100 m×100 m was set on the eastern slope of Sejila, which was divided into 25 (20 m×20 m) by the adjacent grid, and the coordinates, breast diameter, base diameter, crown width and other information of the plants with base diameter ≥ 0.1 cm were recorded. The diameter characteristics and spatial distribution patterns in 12 diameter classes and 6 age classes (seedlings, saplings, juvenile trees, adult trees, big trees, and old trees), graded by base diameter and breast diameter, were analyzed. The results show that (1) the distribution of Abies georgei var. smithii at different diameter levels is inverted "J". (2) The overall population, seedlings, and saplings show the cluster distribution, random distribution, and uniform distribution with the increase of spatial scale, respectively; and juvenile trees, adult trees, big trees, and old trees are randomly distributed within the studied scale. (3) Seedlings are close to or negatively associated with saplings at a smaller scale, and there is no significant correlation at the medium and larger scales. The correlation of juvenile trees, adult trees, big trees, and old trees with seedlings and saplings in spatial distribution is consistent with the Janzen-Connell hypothesis, whereas there is no significant correlation between the former size classes. The above results show that the Abies georgei var. smithii in Sejila Mountains tend to be stable growing; trees of small diameter shelter each other in a cluster to improve their adaption to the environment; trees of large diameter inhibit understory regeneration at smaller and medium scales, while promote regeneration at larger scales. The results would contribute to the revealing of the status and dynamics of Abies georgei var. smithii in Sejila Mountain, and thereby provide a theoretical basis for further study on the maintenance mechanism of the population.