For spruce1fir forest, broad1leaved forest and Changbai larch forest, diameter data that Yu measured and collected in 1980 and 1986 were used to calculate biomass of spruce1fir trees in 1995. Because broad1leaved forest and Changbai larch forest are deciduous forests, not changing much among different years, biomass in 1995 can be directly derived from those in 1986. The results agreed with the measured values from Li et al. (1981).