The study examined the carbon budget of plant communities within regenerated brownfield landscapes, aiming to elucidate the influence of community structure and trait factors on carbon budget levels under specific site conditions. Hangzhou Tianziling Ecological Park served as the research site, with twenty-five plant communities selected as subjects. Hangzhou Tianziling Ecological Park served as the research site, with twenty-five plant communities selected as subjects. Annual carbon sequestration and carbon emissions of these communities were estimated utilizing Drone modeling, the i-Tree Eco model, and the Life Cycle Assessment (LCA) method. The relationship among canopy density, planting density, and the carbon budget level of plant communities was explored, and the impact of plant trait factors on carbon sequestration was discussed, with the intention of improving the carbon budget performance of plant communities in regenerated brownfield landscapes. The study examined the carbon budget of plant communities within regenerated brownfield landscapes, aiming to elucidate the influence of community structure and trait factors on carbon budget levels under specified site conditions. The results demonstrated that: (1) The optimal carbon budget performance was achieved when canopy density ranged from 0.50 to 1.00; plant communities with canopy density below 0.50 were predominantly identified as carbon sources. (2) The highest carbon budget was observed at planting densities between 1 200 and 1 600 plants·hm-2. (3) Diameter at breast height (DBH) and basal area were identified as the primary factors affecting carbon sequestration, with correlation coefficients approaching unity. Conversely, the correlations between crown width, leaf area, and leaf biomass, as well as carbon sequestration, varied depending on the plant species. The carbon budget of plant communities will be affected by plant trait factors, community canopy density, and planting density. During the future construction of regenerated brownfield landscapes, plant community structure will be optimized, and canopy density and planting density will be controlled.