Abstract:In the process of biomass study,underground biomass was very important,but it was often ignored.In this paper,were the four main methods used in studying:soil monolith,soil coring,ingrowth soil core,and minirhizotron.And then,we concluded the rule of underground biomass changing in space and time.We also discussed the effect of environmental factors on underground biomass such as precipitation,heat, reclamation,grazing and the turnover of underground biomass.