Soil organic carbon (SOC) is an important indicator to measure the land desertification. Yulin city is taken as a case to study the SOC dynamics of desertification rebuilding area in a local scale. The data source based on the second soil survey in year of 1982 and repeated soil sampling in year of 2003, and the methods for sampling, determining and analyzing of SOC are auger hole method, K_2Cr_2O_7 oxidation method, area-weigh method respectively, and micro-pipette method is used to determine soil texture. The main conclusions are as follows: SOC content is much correlative to soil texture, it is negative correlation to coarse silt(R=-0.50, a=(0.01)) and positive correlation to clay(R=-0.45, a=0.05); The content, density and storage of SOC in original profile, 1 m depth and arable layer increase greatly during the 20 years, among which the arable layer is most remarkable result in direct and indirect mankind activities; The content, density and storage of arable layer SOC are increased by 0.55 g/kg,0.15 kg/m~2,10.07GgC respectively, which representing rate of increase of 21.00%,(33.02)%,33.02% correspondingly. The results show that tree and grass planting, return plantation to woodland or pasture, sustainable agricultural managements and other countermeasures will promote desertification reverse significantly, which will helpful to increase the amount of SOC and carbon sequestration in desertification area.