Abstract: 50yearold Larix olgensis plantation in montane region of eastern Liaoning Province was selected with different density, branches were effectively collected. The correlations among biomass of these branches and leaves, basal branch diameter and branch length were analyzed respectively to establish model. The CAR model was introduced into the branches volume. The results showed that the biomass models, with the branches volume as parameters, are better than the traditional CAR model. The determination coefficients (R2) of total biomass model of branch and leaf (Wbl=1915682d-0315V) was up to 0983 and forecast accuracy increased by 273%. R2 of branch biomass model (Wb=1793800L-0208V) was up to 0994 and forecast accuracy increased by 915%. R2 of leaf biomass model (Wl=3387837 (d2L)-0427V) was up to 0701 and forecast accuracy increased by 161%.