Abstract: The plantation of Eucalyptus dunnii was used as the research object in this study. The SPSS analysis software was adopted to establish regression model between organ biomass and DBH, height of E.dunnii, and the optimal model was selected to reveal the distribution regularity of biomass of Eucalyptus plantation. The results showed that the vertical distribution of overall trend for biomass of each organ was consistent in three plantations, but growth differences of different plantations made a variation of biomass in E. dunnii in the distribution of different vertical height. The trunk biomass below l/2 of tree height in mountain forest 2 was the biggest, mountain forest 1 was the second, riparian forest was the smallest. But biomass of all different organs was the biggest in riparian forest. Biomass of leaves was distributed in the middle of canopy. The biomass and volume of E. dunnii plantation showed obvious regularity of the distribution for diameter order.