Abstract: Abstract：At present, the estimation of soil carbon reserves constitutes a basic problem in studying the global atmospheric carbon cycle. Based on soil carbon data obtained by multi-purpose geochemical survey in Hebei Province, the authors calculated the soil carbon reserves accurately according to soil types and land use classification so as to estimate soil carbon reserves in the southern plain of Hebei Province, with the adoption of the concept of unit carbon content in the GIS platform. The results show that the soil organic carbon reserves in the southern plain of Hebei Province come to 819402498 t, and their average soil organic carbon reserves are 13206.1 t/km2.