The Baekdu-daegan has been regarded as the most crucial target in terms of social and cultural value in Korean forests, as well as from the perspective of the nation's natural ecology. To understand the vegetation situation of Quercus mongolica-dominant communities, which account for about 53.71% of the existing vegetation area as a representative species of Baekdu-daegan, 141 vegetation structure communities were surveyed in 34 major strategic mountains and peaks. TWINSPAN analysis divided these into four communities, and DCA analysis results showed that Communities I and II tended to be densely distributed on the right side of the first axis. Communities III and IV were distributed in the lower and upper left quadrants based on the second axis, indicating discontinuity with other communities and differences in species composition among the plant communities that appeared. The vertical distribution of Q. mongolica in Korea was found to be related to latitude, and species that share the same range in both horizontal and vertical distributions included Acer pseudosieboldianum, Acer pictum thunb. var. mono, and Fraxinus rhynchophylla, which were classified as indicator species. The relative dominance value results for each community suggested that the existing Q. mongolica communities are expected to face long-term competition with deciduous broadleaf tree species in the understory and shrub layers. Q. mongolica communities located in high-altitude areas are expected to either maintain themselves as climax forests or co-occur with evergreen conifers due to their adaptability to the site-specific environmental characteristics. The distribution environment of Q. mongolica communities in Baekdudaegan spans a wide range horizontally and vertically, and species composition changes in response to increases in latitude and altitude.