Abstract: Carbon is the main element of biological material, especially of plant matter. The carbon content accounts for half of the total dry biomass, so the biosphere is a big carbon pool and the carbon content of terrestrial ecosystems has significant effects on carbon biogeochemical cycling. When the carbon content of the biosphere decreases, most of the carbon is released to the atmosphere and causes the concentration of carbon dioxide in the atmosphere to increase greatly. CO2 is a green house gas; increased atmospheric concentrations will cause increased warming of the climate. In recent years, with increasing usage of fossil fuel and the destruction of natural ecosystems, the increasing release of CO2 from those processes caused the temperature of the earth’s surface to rise and then gradually level at a higher standard. The carbon cycling in forest ecosystems is closely related to CO2 concentration in atmosphere, has an obvious effect on composition of atmospheric elements, and so can influence global climate change. This study focused on the carbon distribution among each component of a typical temperate forest ecosystem of the Beijing area, China. The forest belongs to the warm temperate zone, with a continental monsoon climate which shows clear seasonal periods, dry and cold in winter, warm and humid in summer. The mean annual temperature averages 4.8℃, -10.1 ℃ in January and 18.3 ℃ in July. The annual precipitation amounts to 611.9 mm, 78 percent occurring in June, July and August. The soil is dominated by mountain brown earth. At the research site, the forest is dominated by Quercus liaotungensis, and also includes Betula dahurica, Acer mono, Populus davidiana, Betula platyphylla, Fraxinus rhynchophylla and other related species.We attempt to set up a numerical estimation of forest carbon cycling that will provide parameters of a future computer model. The carbon cycle includes many processes of a forest ecosystem, and so it is difficult to accurately estimate the amount of forest ecosystem carbon. A numerical model of the carbon cycle in this forest ecosystem was established based on studies of this warm temperate deciduous broad-leaved forest ecosystem over 10 years. The data we used in this paper are forest biomass, productivity, biogeochemical cycle, and related published results. We processed, analyzed, integrated, and transformed all the data. Finally we used a comparative method to get more insight on the carbon cycle among different forest ecosystems.Our results showed that a typical forest ecosystem in warm temperate region absorbed 10.3 t·hm-2·a-1 carbon from the atmosphere through photosynthesis. Carbon released to the atmosphere from plant respiration was 5.5 t·hm-2·a-1, with 4.8 t·hm-2·a-1 accumulated in dry plant biomass, and 2.46 t·hm-2·a-1 emitted to the atmosphere by decomposing plant litter. Most carbon assimilated by forests was respired and decomposed to the atmosphere, with little retention in living or dead biomass. Investigation on C storage of warm temperate forests found that carbon-standing amount was 165.05 t·hm-2, with 61.2 t·hm-2 in living biomass, 104.05 t·hm-2 in dead biomass (including soil carbon), and 96 t·hm-2 stored in the soil. The soil C storage in the forest studied accounted for 58% of total forest carbon, and therefore we concluded that carbon in the forest soil is the main storage pool of the forest. C storage change in the forest soil will definitely affect C change of forests in the entire region greatly.