Soil organic C plays an essential role in carbon cycle and carbon storage in a native ecosystem reflects that ecosystem.s capacity to sequester carbon.Based on soil map of China(1:4 000 000)combined with a soil database from the second soil survey of China,soil organic carbon storage to the depths of 100 cm and 20 cm were estimated for China using geographical information system.Carbon density of different soil types ranged from 1.19 kg m^-2 to 176.46 kg m^-2 at depth of 100 cm,and from 0.27 kg m^-2 to 53.46 kg m^-2 at depth of 20 cm.In total,about 84.4 Pg was stored in 0~100 cm,and 27.4 Pg in the 0~20 cm soil layer.The amount of carbon varied significantly at different districts in China.Northeast China, the south and east of Qinghai-Tibet Plateau and southwest China had high carbon density.Tarim Basin,Caidam Basin,Junggar Basin and other desert ification districts had low carbon density.This distribution showed an important climatic influence.Soil organic carbon would diminish with decreasing precipitation and increasing temperature.On the other hand,the activities of human beings may affect the range of soil carbon.