Based on the field sampling survey，the typical saline-alkali soil in three different salinization degrees in the Hetao plain of Inner Mongolia was used as the research object to study the vertical distribution (0 ～ 100 cm) characteristics of soil organic carbon and microbial biomass carbon，and the relationships between the soil organic carbon and microbial biomass carbon and environmental factors were explored.Results showed that the order of soil organic carbon and microbial biomass carbon in different salinization degrees was:mild salinization soil > moderate salinization soil > severe salinization soil，and there were significant differences in the contents of soil organic carbon and microbial biomass carbon in different salinization degrees.The contents of organic carbon in 0 ～ 100 cm layer soil were 1.96 ～ 6.21，1.90 ～ 5.34 and 1.36 ～ 3.92 g/kg，respectively，and the contents of soil microbial biomass carbon were 61.18 ～ 121.72，41.10 ～ 109.85 and 12.61 ～ 35.73 mg/kg，respectively.In the vertical section，the organic carbon and microbial biomass carbon of different salinized soils decreased with the increase of soil depth.The contents of soil organic carbon and microbial biomass carbon were significantly different in different salinization degrees and different soil layers.The ratio of soil microbial biomass carbon to organic carbon decreased first and then increased with the increase of soil depth，and its spatial variation coefficient decreased with the increase of soil depth.There was a significant correlation between soil microbial biomass carbon and organic carbon contentin different salinization degrees，and the correlation gradually increased with the increase of salinization degree.There wasa significantly negative correlation between soil microbial biomass carbon and soil bulk density，but there was no obvious relativity with soil water content.