Forest is considered as a huge carbon sink on earth to control the increase of greenhouse gases, especially CO2. Studies on capability of forest carbon accumulation are more and more consider recently. Specifically, a study on the capability of carbon accumulation in the Nui Coc Lake Protection Forest at the area of Phuc Triu commune, Thai Nguyen city applying a study method of cut down the tree to determine the correlative equation of tree growth. Based on this study to determine the amount of carbon dioxide absorbed in one forest hectare is 118.356 tons/ha, and in the entire studied area is 25.778.01 tons.