Forest soil carbon storage in China is greatly influenced by natural factors such as forest vegetation, soil properties, site conditions, climate conditions, and litter and root input. The composition of forest vegetation types determines vegetation residual volume in soil and its decomposition rate, which leads to significant variations in the content and distribution of soil organic carbon. With the increase of forest age-chronosequence, forest soil carbon storage increases or fluctuates. Soil physical and chemical properties affect the content of soil organic carbon, while soil carbon storage similarly affects soil structure, root depth, soil effective water capacity and soil biodiversity. Site conditions including altitude, slope gradient, slope direction and slope position also have different effects on forest soil organic carbon storage; climate factors including temperature, moisture and CO_2 concentration play an important role in the accumulation process of forest soil carbon organic storage; soil input from litter and root system may change soil carbon pools.