【Objective】By constructing a vegetation-soil whole-ecosystem carbon storage assessment system, the carbon sequestration capacity of the forest ecosystem in Jiangsu Province is systematically evaluated. The current status and existing issues of forest carbon storage in Jiangsu Province are revealed, providing a scientific basis for formulating effective forest resource management and carbon sink management policies.【Method】Based on the 9th National Forest Resource Inventory data of China (2014—2018), combined with field survey data of typical plots and relevant literature data, the continuous function estimation model of volume-biomass conversion factor was used to estimate the carbon storage and carbon density distribution of forest resources in Jiangsu Province. The distribution patterns of carbon storage among different dominant tree species, age classes, stand origins, and forest types were compared and analyzed. Carbon storage of understory shrub layer, herb layer, and litter layer was estimated based on the biomass density, carbon coefficient of each spatial layer in the ecosystem, as well as vegetation area. In addition, carbon storage of the one-meter-deep soil layer was estimated based on soil organic carbon content and bulk density at different soil depth.【Result】(1) The total vegetation carbon storage of different forest types in Jiangsu Province is 4.752 36×10⁷ t,among which arbor forest accounts for 68.26% of the total carbon storage, with a carbon density of 25.49 t/hm². Bamboo forest has the highest carbon density (35.75 t/hm²).(2) Among different dominant tree species, Populus spp. occupies the highest proportion, and its carbon storage accounts for 56.90% of the total. The carbon storage of arbor forests is dominated by young and middle-aged stands, with the order from high to low: middle-aged forests > young forests > near-mature forests > mature forests > over-mature forests. Carbon density shows a trend of increasing with stand age.(3) In terms of different origins, the carbon storage of planted forests is much higher than that of natural secondary forests. Planted forests account for 96.41% of the total carbon storage, reaching 3.127 06×10⁷ t.(4) The order of carbon density among different forest types is: timber forests > protective forests > special-purpose forests > non-timber forests, and the order of carbon storage was consistent with this. Timber forests account for 66.50%.(5) From the perspective of the ecosystem, the total carbon storage of the forest ecosystem is 2.080 4×10⁸ t. The order of spatial distribution of carbon storage in the forest ecosystem is: soil layer > arbor layer > shrub layer > herb layer > litter layer. The carbon storage of the soil layer is 1.588 8×10⁸ t, accounting for 76.37% of the total forest ecosystem carbon storage, followed by the arbor layer(16.16%).【Conclusion】Jiangsu Province demonstrates a substantial growth trend in its forest carbon sequestration. The ratio of aboveground forest carbon storage to underground soil carbon storage is approximately 3∶7. Compared to the national average, the forest carbon density in Jiangsu Province is relatively low, with planted forests as the main type, an excessively high proportion of Populus spp. area, and young and middle-aged stands as dominant forest types. The results provide a data reference for improving the carbon sequestration capacity per unit area of forests, which is conducive to the protection and sustainable development of forest resources—especially the protection of understory shrubs, herbs, and litter layers to increase soil carbon storage and to construct a reasonable forest management model.