SOC plays a significant role in the global C cycle and global warming, and is an important determinant of the physical and chemical properties, as well as productivity of agricultural soils. Regional soil organic carbon (SOC) investigations play an important role in building knowledge of the global soil C cycle system. The purpose of the present study was to estimate soil organic carbon (SOC) storage for different soil types and land uses in Guangdong Province, China. The results showed that the total SOC storage in the study area was 1.25 Pg, of which 0.41 Pg SOC was in A horizon soils (mean depth 17.0 cm), 0.51 Pg SOC was in the B horizon (mean depth 29.5 cm) and 0.33 Pg SOC was in the C horizon (mean depth 48.9 cm). SOC storage in ferrallisols was approximately 0.976 Pg for the total soil profile, accounting for 78.1% of total SOC storage. Forest soils were the main SOC pool by land use, accounting for approximately 80.3% of total SOC storage. Regardless of soil type and land use, subsoil was the primary SOC storage location in the study area. The SOC contents of the upper soil horizon were closely related to the SOC contents of the lower soil horizon, possibly suggesting that there would be the movement of SOC from the surface soil to lower horizons. Because of soil degradation and erosion, approximately 13.3 Tg SOC entered the surrounding water, accounting for 3.2% of the SOC storage of A horizon soils, and approximately 20.9 Tg SOC was redistributed in surface soils of the study area each year.