The improvement of soil capacity of carbon sequestration has great significance for reducing global greenhouse effect. Using two phases' data of organic carbon in surface soil in second soil survey and multi-purpose regional geochemical survey in south Songnen plain and employing variation tendency of organic carbon content in soil in different soil types and land uses in the past 20 years, the authors estimated soil carbon sourcing and gathering potential in different soil types and different land uses in south Songnen plain. The results show that, if the current land use, climate conditions, tillage, and planting technique are fixed, the carbon sequestration potential of soil in the depth of 0-20 cm of cultivated land in Songnen plain is -1.229 Tg C, and the carbon sequestration potential of soil in forestry land is positive in Songnen plain. The data obtained show that the forestry land is a carbon storage area, whose total carbon sequestration potential is 3.169 Tg C, whereas in natural pasture, the data of carbon sequestration potential adds up to - 2.235 Tg C, and the values are mostly negative, indicating a carbon resource area. It is estimated that the carbon sequestration potential of Songnen plain is totally -0.917 Tg C.