Objective  Although soil microbial communities have significant effects on ecosystem construction and function, the researches on them were few conducted in the Three Rivers Source Regions alpine wetlands. Therefore, it is necessary to explore the soil microbial communities and their controlling factors.

  Method  In this paper, using the method of phospholipid fatty acid (PLFA), the soil microbial community characteristics and their controlling factors were studied.

  Result  Results showed that total PLFA was 84.76 ± 38.03 nmol g⁻¹, gram-positive bacteria, gram-negative bacteria, fungi, actinomycete, arbuscular mycorrhizal fungi and other PLFAs were 14.98 ± 6.21, 17.77 ± 8.17, 2.60 ± 1.60, 4.22 ± 2.38, 1.84 ± 1.22 and 43.41 ± 21.06 nmol g⁻¹, respectively. Soil microbial communities were controlled by plant biomass, soil physical and chemical properties, and effects from climate factors were minor. Actinomycete has a positive relationship with soil total nitrogen, soil moisture, NO₃⁻−N, and belowground biomass. Total PLFA and bacteria have a positive relationship with soil total nitrogen, soil humidity, NO₃⁻−N, NH₄ ⁺ −N, negative relationship with bulk density. Gram-positive bacteria have positive relationships with soil total nitrogen, soil moisture, NO₃⁻−N, NH₄ ⁺ −N and belowground biomass. Gram-negative bacteria have positive relationships with soil moisture, NO₃⁻−N, NH₄ ⁺ −N, and belowground biomass. Arbuscular mycorrhizal fungi and fungi have a weak relationship with biomass and soil physical and chemical properties.

  Conclusion  Plant, soil physical and chemical properties jointly affect soil microbial community structure in Three Rivers Source Regions alpine wetlands, which contribute to deeply understanding biogeochemical cycle in terrestrial ecosystems.