Abstract: A quadratic sampling method was used to investigate plant species and their distribution within an elevation range of 3.5-4.5 km in the middle reaches of the Yalutsangbu River.And 5 typical samples were sampled to reveal the relationship between vegetation and environmental factors.Therefore,38 plant species were discovered in the 5 samples.And herbs as well as shrubs have the most species,with the precise numbers being 18 and 13 individuals.Regarding to families,Gramineae,with the largest number of any family has 7 species;composite which has 6 species.Furthermore,the analysis on the samples shows that the water availability is the dominate factor affecting vegetation distribution in this region.Specifically,while the elevation increasing,precipitation increases and temperature decreases,moreover,the vegetation coverage and mean thickness increase.In particular,vegetation coverage and mean thickness in the sand bar of river are much larger than those in other places with the same elevation,only because there is no water stress due to water supply from river.In addition,aeolian sand landform distributes widely in this region.It is feasible to increase water availability by conserving soil and water,which helps to promote vegetation coverage and stabilize sand.