To investigate the responses of soil microorganisms in alpine ecosystems under the context of increasing global nitrogen deposition， this study was conducted in an alpine meadow located in the permafrost region of Fenghuo Mountain， Qinghai Province. Five nitrogen addition levels of 0， 1， 3， 6， and 9 kg·hm^-2·a^-1 were established（denoted as N₀， N₁， N₃， N₆， and N₉， respectively）. The results showed that compared with the N₀ treatment， the N₁ and N₃ treatments significantly increased soil organic carbon content and the soil C/N ratio， whereas the N₃ treatment significantly reduced soil total nitrogen and microbial carbon content （P<0.05）. Nitrogen addition increased the relative abundances of bacterial phyla Proteobacteria and Bacteroidota but decreased the abundances of the fungal phylum Ascomycota and the archaeal phylum Thaumarchaeota. The N₆ and N₉ treatments significantly increased the Sobs and Shannon indices of bacterial communities （P<0.05）. Mantel tests indicated that soil C/N ratio and total nitrogen were key environmental factors influencing bacterial communities， while microbial carbon content， urease， sucrase， and phosphatase activities significantly affected fungal communities （P<0.05）. In summary， different microbial groups exhibited distinct responses to nitrogen addition. The diversity of bacterial community was the most sensitive to nitrogen addition， whereas fungal and archaeal communities responded more stably. This study provides a scientific basis for understanding the effects of nitrogen deposition on soil microbial communities in alpine ecosystems.

Nitrogen deposition  /  Qinghai-Tibet Plateau  /  Microbial community  /  Alpine meadow