Abstract: Characteristics of the spatial distribution of plant communities in wetland ecosystems,Lake Eric and the middle and lower reaches of the Tarinm River,in arid region and their main influencing factors were studied.The plant communities therein were classified with the two-way indicator species analysis(TWINSPAN)method,and the classification was verified with the detrended conrrespondence analysis (DCA) method.Relationships of the vegetation with eight soil environmental factors were quantitatively analyzed.In the studied quadrats,a total of 38 plant species were found belonging to 15 families,35 genera.Using the TWINSPAN method,the plant communities in the 41 quadrats were sorted into seven types,of which each had a constructive species,i.e. Haloxylon ammondendron,Populus laurifolia,Phragmites australis,Populus euphratica,Halostachys caspica,Tamarix hispida,and Salicornia europaea,separately.DCA ordination revealed that soil water content and TP content are the major environmental factors controlling distribution of plant species in the studied zone.