The objective of this study was to examine the effects of long-term N and P addition on soil microarthropod communities in alpine meadows. Three addition treatments of N fertilizer (N), P fertilizer (P) and a NP mixed fertilizer (NP) were set up in Hongyuan County, northwest Sichuan, in late May 2012. Each treatment included three fertilization gradients of 10 g/m² (N₁₀, P₁₀ and NP₁₀), 20 g/m² (N₂₀, P₂₀ and NP₂₀), and 30 g/m²(N₃₀, P₃₀ and NP₃₀) with six replication plots in size of 3 m×3 m. Another six plots of alpine meadow without N and P addition were used as control treatments (CK). Investigations were conducted on the soil microarthropods and environmental factors in each plot in August 2017. Soil microarthropods were extracted from the soil samples for 48 h at 38℃ using the Tullgren method in the laboratory. The results showed that (1) the taxonomic composition structure of soil microarthropod communities was markedly influenced by N, P and NP additions, and the taxonomic richness of mites and insects were increased more significantly by NP mixed additions than N or P addition. (2) The individual density, taxonomic richness and Shannon diversity index of soil microarthropod communities increased significantly in the treatments of N, P and NP additions (P<0.05), and reached to maximum values at the fertilization gradient of 20 g/m². (3) The individual density, taxonomic richness and Shannon diversity index significantly and positively correlated with soil total P (P<0.05). The results demonstrated that additions of N, P, especially NP, changed the taxonomic composition structure, and increased the individual density and diversity of soil microarthropod communities in alpine meadows on Qinghai-Tibet Plateau. We recommended to add the N and P equal mixed fertilizer to alpine meadows at total amount of 20 g/m², to promote the soil microarthropod diversity and ecological functions.