Aiming to explore the aboveground biomass allocation patterns of Daxinganling and establish additive allometric biomass models for Quercus Mongolica species, a total of 78 trees were destructively sampled and collected for wood, bark, branch and leaf biomass. Of which, 31 trees were selected to excavate and collect root biomass. For each component, the share of biomass allocated to different components was assessed by calculating its ratio. The optimum biomass model for each component was decided by using the diameter, tree height, and crown width as independent variables. Seemingly unrelated regression method was applied to construct an additive system of biomass models for aboveground components. Models were validated by the leaveoneout crossvalidation method. The results showed that wood biomass occupied more than half of the aboveground biomass. With the increase of DBH, the wood biomass ratio was relatively stable, branch biomass ratio was increased, while a reverse trend was found for bark and leaf. The root/shoot ratio was decreased rapidly and then slowed down, with an average value of 036. All biomass models showed good fitting results with R2Adj in the range of 0.907~0.984. The root biomass model with the diameter as the sole independent variable showed the optimum fitting effect. The combination variable of diameter and height provided the lowest estimation errors in the regressions associated with wood and bark while using both diameter and crown width as the independent variable generated the most accurate models for branch and leaf. It was concluded that the allometric equations would provide important tools for biomass accounting of Quercus Mongolica distributed in Daxinganling mountains.