To reveal the distribution characteristics of soil organic carbon (SOC) and to study the influence of human activities on SOC in Karst area, 22 786 soil samples collected from 2 854 soil profiles were analyzed. Spatial distribution characteristics of SOC under different land uses in Guizhou Province were discussed. Combined with the control plan of rocky desertification in Guizhou Province, carbon sequestration caused by rocky desertification prevention and control was assessed. The results indicated that the SOC content in Guizhou was high, and the SOC density was low. The average SOC content in top soil (0 - 20 cm) was 25.07 g/kg, but the average SOC density was only 4.27 kg/m2. The SOC content of top soil in different land uses followed the order: shrub lands > arbor-shrub mixed forest lands > shrub grass lands > arbor forest lands > abandoned lands and uncultivated lands > grasslands > paddy lands > garden lands > arid lands and sloping croplands. The SOC density of top soil in different land uses descended in the order: paddy lands > shrub lands > arbor forest lands > arbor-shrub mixed forest lands > abandoned lands and uncultivated lands > shrub grass lands > arid lands and sloping croplands > grasslands > garden lands. The SOC content of top 60 cm soil was sensitive to human disturbance, and small discrepancies were observed among SOC contents of different land uses in deeper soil layers. If the rocky desertification prevention and control project (including returning farmland to forests, construction of artificial pasture, and artificial afforestation) was carried out efficiently, the SOC storage in Guizhou Province would be obviously promoted. Up to year 2050, at calculating depth of 0 - 10, 0 - 20, 0 - 30 and 0 - 100 cm, the total SOC sequestration caused by this project would be up to 1.99×1013, 3.37×1013, 4.45×1013 and 6.29×1013 g. In conclusion, the SOC of Karst areas was characterized by high content and low density, and the implementation of the rocky desertification prevention and control project was propitious to carbon sequestration in Karst areas.