Abstract: To understand the characteristics of soil organic carbon and its correlations with soil properties in the three original Pinus koraiensis forest types in XiaoXing' an Mountains of northeastern China, Picea sp. - Abies sp. -Pinus koraiensis forests, Tilia sp. -Pinus koraiensis forests and Quercus mongolica-Pinus koraiensis forests along elevation gradient were selected for this study, and soil samples were analyzed for soil total organic carbon (TOC), easily-oxidized carbon (EOC), microbial biomass carbon (MBC) and basic properties. Results showed that the contents of soil TOC, EOC and MBC in the three forest types decreased with increase of soil depth. Exception of the depth of 10 - 20 cm, the soil TOC and EOC concentration ranged in order as follows: Quercus mongolica-Pinus koraiensis forests Tilia sp. -Pinus koraiensis forests Picea sp. -Abies sp. -Pinus koraiensis forests, it had the same trend as elevation gradient. Soil MBC varied in different soil depths for the three forest types. Soil EOC, MBC and TOC were all significantly related to total N and C/N, and were negatively significantly related to soil bulk density. We concluded that the combined effects of forest type, elevation, and soil environment contributed to the differences in the soil organic carbon found across the three original P. koraiensis forest types.