Chloroform fumigationextraction were employed to study the content of soil microbial biomass. We choose three typical communities which in Yanchi County of Ningxia desert grassland as the research object, to determine the changing characteristics of soil basic physical and chemical properties and soil microbial biomass carbon and nitrogen, in different soil layers (0-5,5-10,10-15 cm) of two soil habitat in different communities (Caragana korshinskii, Artemisia ordosica, Stipa breviflora), The results show that: (1) the study area of C. korshinskii community, A. ordosica community and S. breviflora community of soil microbial biomass carbon (MBC) concentration range were 77.00-393.18, 17.27-221.71 and 81.05-173.37 mg/kg, soil microbial biomass nitrogen (MBN) concentration range were 7.59-64.81, 1.43-13.95 and 4.25-22.13 mg/kg, At the same time, the soil MBC and MBN have the same rule the content is continuously reduced with the depth increase which performed “fertile island” and the canopy content is higher than that in plexus in the same depth. (2) Community types had significant effects on the changes of soil microbial biomass carbon and nitrogen contents. Under the 3 typical communities,the content of the soil microbial biomass (qMB), carbon nitrogen ratio (SOC/TN) and microbial biomass carbon and nitrogen ratio (MBC/MBN) range were 0.76-4.10, 15.02-52.50 and 5.34-23.07, respectively. Analysis showed that the ratio in different habitats and different depth of soil layers has obvious difference, besides, the correlation of MBC, MBN, SOC, C/N and qMB in the soil of the 3 typical communities reached significant or extremely significant level. (3) Considering the soil MBC,MBN and soil nutrient indexes have the same change trend, the soil MBC, MBN can evaluate the quality of the soil as a biological indicator on a degree.