Abstract: We systematically studied the individual and modular biomass dynamics of Lespedeza bicolor Turcz. populations in western mountain areas of Beijing. Except for the biomass of reproductive modules, which followed the power function, the biomass accumulation of other modules could all be expressed by the equation Y=axb. The individual and modular aboveground biomass of different populations within different habitats significantly differed (P<0.05), and were greater for populations in the forest edge mountain ridge at 910-1 100 m than for other populations. The ratios of vegetative modular biomass were low and that of reproductive modules high in the most compatible habitat for L. bicolor Turcz. populations. The incompatible habitats had the opposite results. The individual growth and modular biomass accumulation were closely related to habitat conditions. The ratios of branch modules increased but that of leaf modules decreased with increasing age, whereas the ratios of reproductive modules first increased and then decreased. Depending on the relation index (R2), the model m(DW)= a(D2H1)b was selected for branch, vegetative modules and individual biomass and the model m (DW)=a(D)b for leaf and reproductive module biomass.