[Objective] The long-term effects of Pinus sylvestris var. mongolica afforestation on soil particle composition and carbon sequestration in Mu Us Sandy Land were studied in order to provide a scientific basis for comprehensive evaluation of ecological environment effects of vegetation restoration.[Methods] Artificial Pinus sylvestris with different shelterbelt planted years(21 years, 36 years, 56 years) and shifting sandy land were selected as sampling sites on the southeastern margin of the Mu Us sandy land, and 0-30 cm soils were collected and analyzed layer by layer to explore the long-term effects of plantation construction on soil particle composition and carbon conteunder different particles grades in semi-arid desert areas.[Results] With the increase of planting years, the soil particles became finer gradually, and content of fine particles in the surface layer(0-5 cm) were higher than beneath layers(5-30 cm). The contents of soil organic carbon(SOC) and inorganic carbon(SIC) increased significantly after shelterbelt construction, and the highest values were 4.90 times and 4.32 times of the shifting sandy land, respectively. The effect of shelterbelt age on SOC content and SOC density(SOCD) was more significant than SIC content and SIC density(SICD). Compared with the shifting sandy land, SOC and SIC contents of each particle size increased most obvious in the shelterbelt planted for 56 years, and the increase of amplitude was largest in fine sand. There were significant linear correlations between organic carbon content of aggregate and silt-clay and total soil organic carbon content, respectively(p<0.01). The contribution rates of organic carbon in coarse sand and silt-clay to total organic carbon, inorganic carbon in silt-clay to total inorganic carbon were significant, respectively(p<0.05).[Conclusion] The contents of soil aggregates and silt-clay particles and soil carbon sequestration capacity were significantly improved with the increase of Pinus sylvestris shelterbelt age.