Abstract: Based on the continuous forest inventory data of Shanxi Province in 2005, 2010 and 2015, it was estimated that the carbon storage and carbon density of main natural forests by biomass expansion factor (BEF) method. The results showed that, the area and volume of the main natural forest increased in 2005-2015. Shelter forest was the main body of natural forest resources in Shanxi Province, representing the largest area and volume. Quercus spp. were the main forest stand, the carbon storage accounted for 45.03%, 46.96% and 33.98% of all natural forest carbon storage in 2005, 2010 and 2015. Picea asperata mast carbon density was the largest (63.56-74.49 Mg/hm²). The other type of forest was the least (17.44-19.96 Mg/hm²). The carbon density of natural forest in Shanxi Province was 29.27 Mg/hm² in 2005, 31.22 Mg/hm² in 2010 and 35.33 Mg/hm² in 2015.