In order to explore the influence mechanism of desertification on the soil organic carbon (SOC) and soil inorganic carbon (SIC), we studied the distribution characteristics of SOC and SIC in bulk soil and their different particle sizes by spatial method instead of time method during the desertification process of desert grassland in Yanchi County. The results showed that:(1) The SIC and SOC contents in 0-10cm soil layer declined with the increasing desertification of desert grassland. The rank of SIC and SOC contents in each particle size of semi-fixed dunes and mobile dunes were soil inorganic carbon of clay and silt (CSIC) > soil inorganic carbon of fine sand (FIC) > soil inorganic carbon of coarse sand (CIC), soil organic carbon of fine sand (FOC) > soil organic carbon of coarse sand (COC) > soil organic carbon of clay and silt (CSOC). (2) The rank of SOC, SIC and STC densities in 0-30 cm soil layer were desert grassland > fixed dunes > semi-fixed dunes > mobile dunes. Compared with desert grassland, SOC and SIC densities in fixed dunes, semi-fixed dunes and mobile dunes declined by 18.5%, 57.7%, 60.5% and 6.7%, 35.9%, 47.0% respectively. (3) The SOC and SIC contents in different particle size fractions of 0-10 cm soil layer and SOCD and SICD of 0-30 cm soil layer were significantly positively correlated with SOC and SIC contents in bulk soil, and CIC and COC had the greatest influence on SOC. The SIC in bulk soil were significantly negatively correlated to CSIC and CSOC. Therefore, desertification control is extremely important to reduce soil carbon loss in desert grassland.