Abstract: Abstract: The impact of agricultural land use on soil carbon storage is one of the international scientific focuses in climate-change mitigation. Aimed to understand the effect of agricultural land development and utilization on soil carbon storage, a study was conducted in different period of farmland at the Fubei Farm of Sangong River Basin in Xinjiang, northwest of China (87?49?-88?16?E, 43?50?-44?22?N). The agricultural lands were selected within different land use years such as 1, 5, 15, 30 and 50 a in the studied area, and the wasteland with little disturbance was selected as a reference land in the same soil type and near position of cropland. Soil samples from these sites were obtained by handy soil auger at 20 cm intervals in a depth of 200 cm and analyzed in the laboratory. Samples were air-dried and crushed to pass through a 2-mm mesh. The patterns of soil carbon storage and its dynamic change were analyzed and compared with the depth of 0-200 cm in recent 50 years, including soil organic carbon, soil inorganic carbon and soil salinity. The results revealed the following: 1) Soil carbon content generally increased with land use years. Soil inorganic carbon content changed by soil depth, with a maximum value of 20.96 g/kg at 180-200 cm. Soil organic carbon presented an opposite trend with the maximum value of 9.51 g/kg at 0-20 cm; 2) In the soil profile, The coefficients of variation of soil carbon content (including organic carbon and inorganic carbon) was gradually increased to moderate intensity variation in 0-80 cm, and then rapidly reduced by more than 40% underneath 80 cm, indicating that the long-term agricultural land development and utilization in arid area had a significant impact on the distribution of soil carbon at 0-80 cm. The variability of soil inorganic carbon and soil total carbon tended to be enhanced with the land use years, while the organic carbon tended to weaken in recent 50 years; 3) The ratio of SIC to SOC increased with the depths of soil layer, and it changed from 0.028 in wasteland to 0.08 in 50 years of cropland (P<0.01). It suggested that the proportion of soil inorganic carbon increased with soil depth and land use years, indicating the role of soil inorganic carbon was enhanced in the long-term agricultural land use process in arid area; 4) During the development and utilization of agricultural land in the past 50 years, the soil carbon storage increased significantly at 0-200 cm depth of soil profile, which was a typical process of carbon sequestration in the studied area. The increased soil inorganic carbon storage and organic carbon storage were mainly showed in 100-200 cm and 0-100 cm respectively. But the amounts of carbon source/sink were different in the soil layer and land use years; 5) Soil salinity showed a decreasing trend along with land use years. Compared to value in wasteland, soil salinity decreased by 655% in land use of 50 a (P<0.001). The linear fitting of salinity and carbon content showed that there was a significant negative correlation between salinity and soil inorganic carbon and total carbon (P<0.10), while no significant correlation with the soil organic carbon (P>0.05). The results showed that the agricultural use leads to an obvious C sink in the soil only in the long term.