By applying the method of quantification theory I , five mathematical equations for estimating the biomass of natural Caragana microphylla brush have been established. Those models may be used for calculating fresh and dry weight of brush, dry weight of, leaves, tender and large branches. Average height, average diameter at ground, number of plouts and growth state are the four factors affec-tiag biomass. Among those factors, the number of plants plays the most important role.