Soil organic carbon is the important part of terrestrial carbon pool, it plays an important role in climatic change and global carbon cycle, and the accurate estimation of soil organic carbon storage (SOCS) is one precondition of its research. Taking Guangdong Province as an example, the top SOCS was estimated by applying the second national soil survey data (341 profiles) and soil type map, as the same way, the soil organic matter degree map based on huge number of soil profiles data was used to calculate the range of SOCS, the accuracy of regular data were also analyzed. The result indicated that: the SOCS using regular soil profiles data was more than the SOCS mean value of new data about 24.81%, up to 1.360*10~8 t, about 0.739*10~8 t and 0.469*10~8 t in laterite red soil and paddy soil respectively. It could be inferred that the result by soil profiles data was overestimated the real SOCS. Different data sources had their own limitations and advantages. Therefore, the range of SOCS using the soil organic matter degree map would doubtless serve as a powerful supplement in the SOCS estimate methods, as well as province necessary reference for the SOCS true value.