[Objective] We took the fescue and miscellaneous grass meadow steppe in the north slope of Tianshan mountain as the research object in order to study the effect of cutting intensity on aboveground and underground biomass of grassland.[Methods] Four treatments including no grazing, light grazing, moderate grazing and heavy grazing were set to investigate the biomass of grassland ecosystem.[Results] With the increase of grazing intensity, herbaceous biomass and litter decreased, and this decrease trend increased gradually. Compared to the no grazing treatment, biomass in light grazing, moderate grazing and heavy grazing were decreased by 27.51%, 45.28%, 65.05%, respectively. The underground biomass of no grazing, light grazing, moderate grazing and heavy grazing in September increased by 16.05%, 13.07%, 19.15%, 19.08%, respectively, from June. Biomass in 0-20 cm soil layer accounted for 85% of the total underground biomass, and the decreasing trend of underground biomass with the increasing soil depths was obvious.[Conclusion] The effect of grazing intensity on aboveground biomass was:light grazing >no grazing >moderate grazing >heavy grazing. The maximum aboveground biomass occurred in July, which was significantly higher than that in September. The effect of grazing intensity on the underground biomass in 0-100 cm soil depth was light grazing >no grazing >moderate grazing >heavy grazing. The vertical distribution trend of underground biomass was the same in all different grazing intensities. Underground biomass mainly distributed in 0-10 cm soil layer, and it accounted for 70% of the total underground biomass. In addition, underground biomass reduced with the increase of soil depths. Variations in underground biomass were great in September than in June.