Abstract: The effects of parent materials on soil organic carbon (SOC) should not be ignored.This paper took Juhe watershed in Sanhe County, Hebei Province as the research object to discuss the difference of soil organic carbon density (SOCD) in different soils and influencing mechanism by their parent materials.According to the sedimentary environment of Holocene, the parent materials in the area were divided into alluvial-proluvial facies sediments (APFS), alluvial facies sediments (AFS) and lacustrine facies sediments (LFS).It was shown that there were significant variations of SOCD between soils developed in various parent materials via one-way analysis of variance, following the order AFS < APFS < LFS.Furthermore, the texture, nutrient elements concentrations, as well as physicochemical properties of soil, were comparatively analyzed, indicating that the influences of parent material on SOC were reflected on the influences of physicochemical property of soil on vegetation growth and development, the activity of soil flora, fauna and microorganism, and on the sequestration of organic carbon.From AFS, to APFS and to LFS, soil clay fraction gradually increased, which protect SOC from being decomposed by microorganisms since SOC were subjected to be coordinated with clay minerals into organo-mineral complex.On the other hand, LFS and APFS were characterized by more abundant water and nutrients than AFS, which contributed to vegetation growth and then input of SOC.In addition, microbial activity was strengthened, whose metabolites and residues after death are crucial source of SOC, increasing the storage of SOC.Our results could provide technological supports for the conservation and utilization of SOC in the Juhe watershed.