Abstract: To reveal the dynamics of organic carbon in the soil profiles of a open-pit coal mine in loess area，and taking the farmland，woodland and grassland in different reclamation phase in Pingshuo mine dump as research targets，the profile distribution of soil organic carbon (SOC) and its relationships with soil pH，total nitrogen and w(C/N) under different reclamation directions were studied.The results indicated: the profile distribution of SOC varies with soil depth and reclamation direction; the SOC vertical distribution in different reclamation directions exhibits a certain regularity，that is，the organic carbon content decreased with the increase of soil depth; Compared with the dump not being reclaimed，the surface SOC content of farmland that reclaimed for 2 years and 18 years，increased 22.73% and 46.06% respectively，the woodland reclaimed for 18 and 22 years increased 38.86% and 29.55%,the grassland reclaimed for 14 years increased 30.96%,while grassland reclaimed for 18 years changed slightly; the sequence of the organic carbon contents in different reclamation directions from high to low is generally as follows，woodland，farmland and grassland；Significant and positive correlations were found between SOC and total nitrogen under different reclamation directions with R=0.642 in farmland,R≥0.812 in forestland and grassland;SOC are in extremely significant and positive correlation with w(C/N)，with the correlation coefficient greater than or equal to 0.679;SOC content in farmland and woodland have a significant negative relationship with pH，(with R=-0.685 in farmland,R=-0.723 in forestland)，while SOC and pH under grassland has no significant correlation.This study can provide a certain reference for land reclamation and ecological reconstruction of opencast coal mine in Loess area.

Key words: Soil organic carbon, Reclamation direction, Vertical distribution, Dynamic change, Opencast coal mine, Dump