To combat the challenges posed by global climate change, in September 2020, China proposed to strive to achieve carbon neutrality by 2060.However, according to ecological theory, the carbon input and output of mature ecosystems tend to be in balance, and there is no net accumulation of carbon and no carbon sink function, while immature ecosystems have a net accumulation of carbon and a carbon sink function, but any immature ecosystem in nature has been continuously replacing the mature ecosystem since it was established, that is, the end result of any ecosystem succession must be that carbon input and output are in equilibrium.Since forest ecosystems are the largest carbon pools in terrestrial ecosystems, their contribution to carbon neutrality is highly expected.Therefore, taking mature forest ecosystems as an example, considering their biomass carbon pools and soil organic carbon pools respectively, and based on the latest global research results, this paper demonstrates that the soil carbon pool accumulation process of mature forest ecosystems has a long-term carbon sequestration function, and does not contradict the ecological theory that the carbon input and output of mature ecosystem tend to be in balance, and it can contribute to the goal of carbon neutrality.