Carbon sequestration forecast at natural forests in national parks and conservation areas, targeting for PFES, need to be studied. The method of non-destructive measurement is used for collecting data through 12 sample plots at the classified forest type as IIB (natural regeneration /rehabilitation forest) in Ba Be National Park. As results shown, there are about 8-17 species in different sample plots. The density is approximate 1,150 - 1,850 trees/ha. Total biomass ranges from 85.69 ton/ha to 276.4 ton/ha, average is 180.33 ton/ha. In general, the carbon sequestration of different forest stands in the research area is significant change from 39.42 ton/ha to 127.14 ton/ha, average is 82.96 ton/ha.