The Natural Forest Protection Program (NFPP), which aims at protecting ecological resources and achieving sustainable forest management, has been implemented for 10 years in Northeast China. Under the program forest ecosystems in the region have been divided into three management areas-Key conservation, General conservation and Commercial forest. Each of these three types of forest land is subject to different management measures (protecting or logging). Estimating carbon storage of forest vegetation in these areas is important both for understanding the capacity of forests in the Northeast region for carbon sequestration and as an aid to assessing the effectiveness of the NFPP in meeting its goals. To address this important need, this study selected five major forest types in the Northeast forest region-larch forest, birch forest, coniferous mixed forest, broadleaved mixed forest, coniferous and broadleaved mixed forest. Each forest type was divided into four age classes-young, mid-aged, premature and over mature forest. Tree biomass was calculated through species-specific allometric equation models based on field measurement in the Daxing'anling, Xiaoxing'anling and Changbai mountains. At the same time, an dataset on biomass and volume of the main forest types in the Northeast forest region was established based on existing data from former studies. Since some studies have found that the relationship between forest biomass and volume fits relatively well within a liner regression framework, this study utilized this two data sources noted above to establish biomass-volume line regression models of the main tree species groups in the Northeast, focusing primarily on the five major forest types identified above. Forest biomass carbon storage in areas under the NFPP in the Northeast region was subsequently estimated based on data from the 7th National Forest Resource Inventory. Results showed that forest biomass carbon storage based on field measurement did not varied significantly with management areas, which likely reflects both the classification standard for the management areas and the relatively short period since the NFPP have been implemented. On the other hand, forest biomass carbon storage of lands under the NFPP was 1045 TgC, which accounted for 68% of total forest biomass carbon storage in the Northeast provinces of Jilin, Heilongjiang and Inner Mongolia. Moreover, forest biomass carbon density of lands under the program (41 Mg/hm²) exceeded that of the average biomass carbon density in Northeast provinces (36 Mg/hm²). Simultaneously, in the lands of the NFPP, forest biomass C density increased with forest age class, from 16.4 Mg/hm² in young to 63.0 Mg/hm² in over mature forest, thus the relative large areas of young and mid-aged forests (together accounted for 61% of total forest area), implying its great C sequestration potential in the future. In addition, forest biomass carbon storage was dominated by natural forest, which accounted for 97% of total biomass carbon storage under the NFPP. On an overall basis, the Natural Forest Protection Program acts an important role in the Northeast forest region, and it should be played an increasingly important role in forest ecosystem carbon sequestration and sustainable forest management in the next implemented decade.