Ten kinds of Panicum virgatum originated in USA were introduced on hill slope and valley plain in the Ansai research station from 1992 to 1998.The data observed for 7 years illustrate that Panicum virga-turn in 3 to 5 year growth fastigium stage particularly requires soil moisture and gives the highest yield. In view of the change in soil water content, Panicum virgatum helps form a dried layer between 80 and 200 cm from soil surface and it can not be compensated by rainfall in growing season, as well as rainfall and snow in leisure time.The problem is resulted from the maintenance for a higher productivity.Panicum virgatum has a strong adaptability in semi-arid hilly and gully region of the Loess Plateau, which is of importance to artifi-cial grassland construction and natural grassland improvement.Through comparing the productivity of Pani-cum virgatum cultivated in the region with the characteristics of soil moisture, the effects of Panicum virga-tum's eco-adaptability on its aboveground biomass formation may be understood.The results offer a scientific basis and an important reference to rational utilization of local herb resources and improvement of grassland productivity.