Abstract: Based on the results of multi-objective regional geochemical survey, taking the Zhalong wetland as an example, the unit reserves of organic carbon are calculated by the analysis for surface(0-20 cm) soil and deep(150-200 cm) soil samples. With comparison of the organic carbon storages in different land use areas, the distribution and variation of organic carbon contents in the soil of wetland are studied. The changes of organic carbon in the wetland soil during the last 20 years reveal an increase in organic carbon reserves, showing a wetland carbon sink.