Abstract: In this paper, a Systematic research is made into the dynamic laws of the primary production and a relationship between Biomass and precipitation in the desert steppe.
During 4 years from 1984 to 1987, in the whole plant growth season span forcvery ycar from the time when plant innovation bud began to germinate and the green leaf appeared until the time when the plant stem and leaf turned yellow and died, we carried out ficld sampling. The sampling method was to surrey the given plot system and regularly, and according to given size area, record the density, height and covertage of every plant population, stove it dry 65℃ and sruvey its weight indoors.
This pape reported. the dynamic laws of above and undergroundB Biomss and interrelation by regresson analysiz between above and underground Biomass and pvecipitation. These results show:
（1）The change of Above ground production is great in diffient years. and it gets up 116.9 g/m² in more raing year and 67.9 g/m² in nomal year and 31.9 g/m² in Arid ycar. Among them, the change of Artemisia is the highest and it is more 10 times than Arid year but the change of Allium remain more stable in raing and arid years the change of under－ ground Biomass is more low and It gets up 70% between the highest and lowest value in ra－ ing and arid years.
（2）The change of production depends on precipitation. There is anthentic regression interrelation between abovegroundproduction and annural precipitation（r=0.99）and fine anthentic regression interrelation between underground Biomass and annural precipitation, so we can foresec the above production and underground Biomass according to anuural precipitation.