Abstract:This study selected the forest soils from 8 regions under different longitudes in the Loess Plateau as research objects, and explored the soil nutrients, soil microbial biomass and their ecological stoichiometry under different longitudes. The results showed that the contents of soil carbon, nitrogen and microbial biomass carbon, nitrogen and phosphorus overall gave a trend of decreasing first and then increasing with the change of longitudes. There was a coupling relationship between soil microbial biomass carbon, nitrogen and phosphorus and soil carbon and nitrogen, and the response to environmental factors was consistent. The spatial distribution of soil phosphorus content was stable. The soil carbon-nitrogen ratio was around 8, and the spatial distribution of soil organic carbon and total nitrogen was consistent. The soil microbial biomass carbon-nitrogen ratio was about 9, and the microbial biomass nitrogen-phosphorus ratio was about 5, which reflected that the soil microbial biomass carbon-nitrogen and nitrogen-phosphorus ratio were relatively stable, but the soil microbial biomass carbon-phosphorus ratio showed a trend of increasing first and then decreasing. Soil microbial biomass carbon, nitrogen and phosphorus had a strong correlation with soil moisture. Soil nutrients and soil microbial biomass carbon, nitrogen and phosphorus and their ecological stoichiometry were the result of the comprehensive action of environmental factors.