We selected Huanghuadianzi watershed in Aohan Banner of Chifeng City in Inner Mongolia as the research area and analyzed the changes in soil organic carbon content, density and storage in different soil layers through geostatistical and ArcGIS methods. The results showed that soil organic carbon content and density decreased from the surface layers to the middle layer then to bottom layers; Carbon density of soil surface decreased with the increase of altitude, but the underlying soil organic carbon content had no obvious change with the change of altitude, moreover, carbon content increased first and then decreased while the effects of altitude on soil organic carbon also decreased with the increase of soil depth. The organic carbon reserve of the study area was 2.04×10⁵ t, and the soil organic carbon reserves of different soil layers were as follows: the middle layer(8.56×10⁴ t) > bottom(6.41×10⁴ t) > surface(5.47×10⁴ t). Soil organic carbon storage has significant correlation with its corresponding area of the given altitude.