Abstract: The stability of forest soil carbon(SOC)at different soil depth profiles showed great discrepancy. It has been found that SOC in the subsoil is more stable than that in the topsoil. The depth distribution of SOC is essential to mitigate the effect of global climate change. Twelve combination plots consisting three forest types(masson pine stand, reforest and mixed forest)and four soil groups(yellow soil, yellow-brown soil, limestone soil, purplish soil)were employed by this study in Zigui county in Three Gorges Reservoir Area. A spatial distribution model for SOC mass density was established by typical sampling method. Applying PTFs(Pedo-Transfer Functions)relating to regression relationships between main parameters of the model and parameters of soil properties were verified. The results showed that forest type had a strong influence on SOC mass density in soil top layer, but soil group no significant. Soil texture determined the SOC density along the whole profile. SOC density near the surface of the profile was remarkably higher in clay textured soils than in sand's. The rate of decline of SOC density with depth depended on texture and forest type. The slower decline of SOC density with depth was in sandy soils than in clay soils. Using forest type and soil texture information, the spatial distribution model could be used to predict the pattern of distribution of SOC density by depth. Applying this established model, the total amount of SOC stored in forest land in Heigou watershed was obtained(5 290.32 ±74.85)t for the top 30 cm and(8 280.87±120.98)t for the top 100 cm. The amount of SOC stored in 0-30 cm accounted for 63.89% of that in whole profile.