Based on the data of soil physical and chemical characteristics from 217 soil samples collected from 31soil profiles located in eight monitoring sections in the lower reaches of Tarim River, southern Xinjiang, we analyzed the spatial patternsof soil properties usingnon-parametric method or ANOVA, and examined the differences in soil quality between monitoring sections by cluster analysis. The relationship between plant species diversity and soil factors was also examined by using grey correlation analysis. Results indicate that the measured soil properties,including the organic matter, total N, and total K varied vertically among different soil layers with exception of the total P, with significant differentiation at 50cm soil depth. Based onsoil quality, the lower reaches of Tarim River aregenerally differentiated between the upper sections and the lower sections, withthe content of nutrientsin soils of the upper parts being greater than in the lower parts. Along the environmental gradients of the different monitoring sections located 150m away from the river course of the lower reaches of Tarim River (namely from upper to the lower sections), plant species diversity indices displayed the same pattern of descending gradient as soil organic matter. Moreover, plant communities showed a change from mixed-species communities to single-species community corresponding to the changes of plant species diversity indices,i.e.from the communities composed of arbor (Populus euphratica), shrub (Tamarix spp.) and mixture of herbage to pure Tamarix community. Grey correlation analysis indicates that there exist significant relationships of plant species diversity with soil organic matter, total N, total P, and total K in the 0-50cm soil layer, suggesting that changes in these soil factors could reflect changes in plant species diversity to certain extentin the lower reaches of Tarim River.