Abstract: In order to explore the changes of biomass and root shoot ratio of single Xinjiang poplar in oasis farmland shelter forest,this paper takes the forest belt structure as the research object, uses the method of spatial series instead of time series to analyze the root biomass of single Xinjiang poplar at different tree ages, and investigates the lateral root biomass of farmland shelter forest by using fixed quadrat, The difference of aboveground and underground biomass density and the change and distribution process of root shoot ratio were obtained, and the model was established to analyze the implied mechanical and biological mechanism of the change and distribution process.