【Objective】Natural arbor forest biomass carbon pool and its changes were estimated for Fujian Province based on inventory data for forest resources. Strategies for increasing carbon sinks have been put forward, which provided a theoretical basis for the improvement of the carbon sequestration capacity and the scientific management of natural forest.【Method】The carbon storage and the carbon density of the natural arbor forest in Fujian Province were estimated based on four sets of forest inventory data from 2003 to 2018 using the continuous biomass expansion factor method, combined with the carbon fraction and the root shoot ratio of the main forest types.【Result】Results showed that the natural arbor forest carbon storage in Fujian Province increased from 156.11 Tg in 2003 to 248.68 Tg in 2018, with an average annual growth rate of 3.15%. The carbon density increased from 47.30 Mg/hm² in 2003 to 76.24 Mg/hm² in 2018, with an average annual growth rate of 1.93 Mg/hm². The carbon storage of the natural arbor forest was dominated by broad-leaved species including mixed coniferous and broadleaved forest. This accounted for more than 70% of the four forest inventory periods up to 86.47%. From 2003 to 2018, the area of young and middle-age natural arbor forest accounted for 58.78%-73.76%,and the carbon storage accounted for 50.72%-61.90%. The area and the carbon storage were predominantly young and middle-aged forest,but the proportion showed a pronounced downward trend. The proportion of carbon storage was significantly lower than that of the area. The carbon density of the natural arbor forest showed a pronounced upward trend with the increase in forest age. The carbon density of the broadleaved species was higher than that of the coniferous species.【Conclusion】The natural arbor forest carbon storage and the carbon density of Fujian Province show a trend of rapid growth, and the carbon sink capacity markedly enhanced. With the continuous strengthening of natural forest protection and ecological restoration, the dominant young and middle-age forest has entered a fast period for growth. There is considerable potential for natural arbor forest carbon sequestration in the future.