Abstract:This paper deals with the seasonal and spacial change of the biomass of aboveground and underground part in Bothriochloa ischaemum community. The results showed obvious biomass seasonal dynamics in B. ischaemum community. The biomass of aboveground achieved peak value (314.66g/m2) in the mid-September. The biomass of underground was minimum during flourishing period and maximum during the withering period. Such change in biomass is relevent to the developmental stages and transport of organic materials.