In order to reveal the ecological role of ants in southeastern Tibet, distribution patterns of ant species from Mount Sejila were investigated for the first time by the sample-plot and search-collecting methods. In total, 31 species belonging to 3 subfamilies and 14 genera of Formicidae are recognized. Among them, 2 genera and 3 species belong to Ponerinae, 7 genera and 17 species belong to Myrmicinae and 5 genera and 11 species belong to Formicinae. In the Mount Sejila area, most of the ant species (about 2/3) are poorly adapted to alpine conditions and found below an elevation of 3 000 m. Relatively few species (about 1/3) can physiologically adapt to higher elevations and found above 3 000 m in elevation. The species richness of ants increases with decreasing elevation. This phenomenon is primarily due to thermal factors (air temperature). The types of vegetation applied by ant species is restricted by air temperature and plant richness. Distribution patterns of ant species are also affected by slope direction and position, which can constrain the local heat accumulation. The direction of the slopes preferred by ants differs from species to species. On Mount Sejila, distribution patterns of ant species in the same genus are very distinct. Myrmica smythiesii Forel and M. bactriana Ruzsky are the most widely distributed species, occupying the widest range of habitats.