In this study, a soil survey was carried out in Aohan County in Chifeng, Inner Mongolia. A generalized additive model (GAM) was used to analyze the spatial variability of the soil organic content (SOC) in soil depths of 0-100 cm. The results showed that SOC varied from 0.23 to 20.71 g/kg in 0-100 cm soil depths, and decreased gradually with increasing soil depths. The GAM fitted the relationship between SOC and environmental factors well. With increasing soil depth, SOC also varied. Vegetation was the dominant factor affecting SOC in surface soil; soil moisture was the dominant factor affecting SOC in deeper soil. The dominant factors that influenced the variation of soil organic carbon also showed considerable differences with increasing soil depth.