Pinus sylvestris var. mongolica plantations are an important part of the ThreeNorth Shelterbelt, playing a key role in wind prevention and sand fixation, and carbon sequestration. To quantify carbon storage dynamics and distribution patterns of these forests with forest age, this study selected different age classes of P. sylvestris var. mongolica plantation in Fujia Forest Farm in northwestern Liaoning Province, including 10-20, 20-30, 30-40 and 40-50 years old to assess tree and soil carbon pools. Tree carbon was estimated through allometric equations that were established for P. sylvestris var. mongolica in northwestern Liaoning, and soil carbon storage was obtained via soil organic carbon content multiplied by bulk density from soil profile. The results showed that:  Tree carbon storage increased with forest age, and carbon storage levels were 20.98, 25.89, 33.83 and 34.94 Mg C·hm^-2 in 10-20, 20-30, 30-40 and 40-50 years old P. sylvestris var. mongolica plantations, respectively; this was mainly attributed to increased trunk carbon storage that accounted for the largest proportion of tree carbon storage, being 47.25%-56.17%.  Soil carbon storage also showed an increased pattern with forest age, with the smallest level of 32.80 Mg C·hm^-2 and largest level of 51.46 Mg C·hm^-2 in 10-20 and 40-50 years old P. sylvestris var. mongolica plantations, respectively. In addition, both soil carbon storage and organic carbon content decreased with the increase of soil depth, with the carbon storage range of 4.57-19.20 Mg C·hm^-2 and organic carbon content range of 0.35%-2.04%, respectively.  Total carbon storage of P. sylvestris var. mongolica plantation also increased with forest age, and carbon storage levels were 53.78, 61.88, 67.48 and 86.40 Mg C·hm^-2 in 10-20, 20-30, 30-40 and 40-50 years old plantations, respectively. It implied that P. sylvestris var. mongolica plantation ecosystem acted as a carbon sink during its growth process. In addition, the contribution of soil carbon storage to total carbon storage ranged from 49.87% to 60.99%, while the contribution of tree carbon storage to total carbon storage ranged from 38.91% to 50.13%. These data were of scientific importance to comprehensively predicting ecological values for ThreeNorth Shelterbelt.