Abstract: Platycladus orientalis and Pinus tabulaeformis are the most important tree species in limestone mountains region. The method used here is to choose the single-species wood to build the math model to measure the biomass per hectare. By using Area Proportion Method to measure the biomass of shrub and herbaceous plant under the tree, the biomass of arbor layer and shrub herbaceous layer from the interblending trees and single-species wood was calculated and analyzed respectively. It showed that the biomass of arbor layer and shrubt; erbaceous layer from the interblending trees was lower than single-spedes wood respective ly. The total biomass, however, of the interblending trees was far higher than single-species wood, which suggested that the policy makers take the interblending trees as the way to afforest in calcareous mountains.