The relationship between the topographic climate factors and species distribution influences the succession and development of alpine vegetation communities and also has great significance to maintaining the functions and structure of mountain water conservation forests. In this study, the water conservation forest at the eastern Qilian mountain was taken as the research object. Based on the investigation data of plant community species composition, the topographic and climatic factors, the characteristics of alpine plant community and its relationship with the topographic and climatic factors were explored by quantitative classification and ordination. The results showed that 181 plant species were recorded in 65 samples belonging to 40 families and 124 genera. The largest family was Compositae (30 species), Rosaceae (17 species), Gramineae (13 species), Leguminosae (11 species), and Ranunculaceae (10 species), which accounted for 16.57%, 9.44%, 7.22%, 6.11%, 5.56% of the total species, respectively. The structure of the community consisted of tree layer, shrub layer, and herb layer, with 8 species of trees, 25 species of shrubs, and 148 species of herbs. The dominant species of tree layer were Picea crassifolia, Sabina chinensis, and Betula albosinensis. Potentilla glabra, Salix oritrepha, Berberis vernae, and Spiraea alpine were the dominant species of shrub layer. The dominant species of herb layer were Carex kansuensis, Polygonum viviparum, Poa annua, Thalictrum aquilegiifolium var. sibiricum, and Artemisia tangutica. TWINSPAN divided alpine vegetation communities into 7 cluster types. Ass.I B. albosinensis-Rosa moyesii-C. kansuensis, Ass.II P. crassifolia-B. vernae-C. kansuensis, Ass. III Sabina chinensis-Spiraea alpine-P. viviparum, Ass.IV S. alpine+ Caragana jubata-P. viviparum, Ass.V Hippophae rhamnoides+A. tangutica+Geranium sibiricum, Ass.VI H. rhamnoides+Ixeris polycephala+Fagopyrum tataricum, and Ass.VII H. rhamnoides-Agropyron cristatum+Comarum salesovianum. Seven clusters were clustered and distributed on the DCA ordination graph, which reflected a good environmental gradient. The CCA ordination results showed that altitude was the most important environmental factor for plant species distribution of alpine vegetation community in Qilian mountains, followed by precipitation, temperature, slope direction, and slope.