Based on the forest resources inventory data of eight times (1977-2018),the biomass expansion factor was used to analyze the carbon sequestration and carbon density of natural forests in Yunnan Province.The results showed that:1)The carbon sequestration of natural forests in Yunnan Province increased from 450.886 million tons in the second inventory to 810.151 million tons in the ninth inventory,with a net increase of 359.265 million tons and an annual growth rate of 1.64%;2)The carbon density of natural forest showed a "rising-falling-rising"trend,carbon density tested in the ninth inventory was 55.79t/hm²;3)In the seventh to ninth inventory,the total amount and increment of carbon sequestration in middle-age forest were the highest,and the order of carbon density in natural forest in the third inventory was overmature forest>mature forest>near mature forest>middle-age forest>young forest,the order of carbon sequestration of different forest species was shelterbelt forest>timber forest>special forest>fuel forest,and the order of carbon density was special forest>shelterbelt forest>timber forest>fuel forest;4)Among the different dominant tree species,Quercus,broadleaves mixed forest,Pinus yunnanensis,mixed coniferous and deciduous forests,other soft wood and Abies fabri were the main contributors to the carbon sequestration of natural forests in Yunnan Province,the order of carbon sequestration increment of different dominant tree species was:broadleaves mixed forest>mixed coniferous and deciduous forests>Pinus yunnanensis>mixed coniferous>Abies fabri,and the estimated carbon density of Tsuga chinensis, Abies fabri,Picea asperata was quite high,with sound growth quality.