【Objective】The carbon storage of a forest ecosystem in Wenzhou City, Zhejiang Province was studied to understand the current situation of forest ecosystem carbon storage and provide data for the evaluation of the regional carbon sink function.【Method】Based on monitoring data from the 10 main forest resource types in Pinus massoniana forest, other pine forest, Cunninghamia lanceolata forest, Cryptomeria japonica var. sinensis forest, Cupressus funebris forest, hardwood forest, mixed coniferous forest, mixed broadleaved forest, mixed coniferous and broadleaved forest, and Phyllostachys edulis forest in Wenzhou City in 2018, as well as the data measured from 30 survey sample plots, the carbon storage and carbon density were calculated for different forest types by using the average biomass conversion factor method. The Pearson correlation analysis method was used to analyze the correlation of organic carbon storage among the different forest ecosystem components.【Result】The carbon storage of the forest ecosystem in Wenzhou City was 81.70 Tg, including 18.46 Tg in the tree layer, 1.55 Tg in the shrub and grass layer, 1.02 Tg in the litter layer, and 60.67 Tg in the soil layer, accounting for 22.60%, 1.89%, 1.25%, and 74.26% of the carbon storage of the ecosystem, respectively. The carbon density of the forest ecosystem in Wenzhou was 123.81 t/hm², including 27.98 t/hm² in the tree layer, 2.34 t/hm² in the shrub and grass layer, 1.54 t/hm² in the litter layer, and 91.95 t/hm² in the soil layer. The soil organic carbon pool was 2.88 times that of the vegetation organic carbon pool. The organic carbon storage of the tree layer and the soil layer represented the main carbon pool of the forest ecosystem, accounting for 96.86% of the total organic carbon storage. In the arbor layer, the highest carbon density was recorded in the cypress forest (46.06 t/hm²) and the lowest carbon density was in the broadleaved mixed forest (20.50 t/hm²). In the soil layer, the highest carbon density was the Cryptomeria japonica var. sinensis forest (136.97 t/hm²) and the lowest was the other pine forests (49.38 t/hm²). There were some differences in the carbon density of the stand ecosystem for different species. The Cryptomeria japonica var. sinensis forest had the highest carbon density (185.42 t/hm²) and the Pinus massoniana forest had the lowest carbon density (83.34 t/hm²). There was a significant correlation between the carbon storage of the tree layer and the litter layer (P < 0.05). There was a highly significant correlation between the carbon storage of the soil layer and the carbon storage of the forest ecosystem (P < 0.01). This indicated that the soil layer contributed the most to the carbon storage of the entire ecosystem. The correlation between other components did not reach a significant level.【Conclusion】The carbon density of the forest ecosystem in Wenzhou was slightly higher than the average level in Zhejiang Province, but was lower than the average level of China. Therefore, improving the forest carbon density through sustainable forest management will be the focus of carbon sequestration forestry in the future in Wenzhou.