In this study, species richness and community composition of vegetation along the southern fringe of the Kumtag Desert were studied, with the effects of 11 climatic and topographic factors also being explored using principal component analysis and variance decomposition. Results showed few plant communities in the study area and single species composition. In total, 38 plant species were recorded, belonging to 15 families and 32 genera. The dominant plant life forms were shrubs and perennial herbs, accounting for more than 80% of all species. Species richness and plant community composition were significantly constrained by hydrothermal conditions. Regression analysis showed that species richness was significantly negatively correlated with the energy factor in the region (P
<0.05), but positively correlated with the water factor (P
<0.05). Variance decomposition showed that water and energy restricted species richness in the region, with these two variables explaining 44.3% of the variation in species richness. In addition, topographic factors had a certain influence on species richness in the study area, which further improved the interpretation rate of environmental factors on species richness. In short, species composition along the southern fringe of the Kumtag Desert was simple. The species richness pattern was constrained by hydrothermal conditions, with topographical changes also playing an important role.