The study of soil organic carbon density and its distribution characteristics in Zhangye-Yongchang area can contribute to the investigation of land utilization, carbon sequestration and regional climate change based on the multi-target geochemical survey. According to the analytical results of average soil carbon density at the depth of 0.2 m and 1.8 m in the study area, the average soil organic carbon (SOC) is much lower than the national value. The SOC at 0.2 m in Shandan Army Horse Ranch is the highest while the SOC at 1.8 m in Shandan Army Horse Ranch and Zhangye has the highest value and is higher than the value at 0.2 m, which should be related to the preservation of organic materials in deep soil. The SOC value of chernozem is much higher than that of black soil and boggy soil. The average values of SOC, SIC and SC in gardens are higher than those of grass which has the lowest values. The average value in peneplain is higher than that in middle mountain and wind-blown terrain which has the lowest value. In brief, the soil type, the land utilization type and the landscape/regional geomorphology can influence the soil carbon density and its distribution.