【Objective】Soil particle composition directly influences soil texture, fertility, ecological functions, and agricultural productivity. Therefore, investigating the environmental factors affecting soil particle composition and its spatial distribution characteristics in the Tarim River Basin is of great significance for soil resource management and ecological environment construction in arid regions.【Method】This study analyzed soil particle composition data from 383 soil layers within 107 typical soil profiles (0~100 cm) in the Tarim River Basin. The Kruskal-Wallis test was used to determine inter-group differences, Spearman’s correlation analysis was employed to examine relationships between climatic factors and soil particle composition, and the random forest algorithm was applied to analyze the influence of environmental factors on the spatial distribution. Model accuracy and variable importance were assessed using R² (coefficient of determination), RMSE (root mean square error), ME (mean error), and %IncMSE (percentage increase in mean squared error) to predict the spatial distribution characteristics.【Result】The results showed that: (1) The soil particle composition within the 1-meter soil profile was dominated by sand and silt particles, with contents of 44.23%, 45.26%, and 10.51% for sand, silt, and clay, respectively. A highly significant negative correlation was found between sand content and both silt and clay contents, while a highly significant positive correlation existed between silt and clay. This suggests weakened pedogenesis in the Tarim River Basin, characterized by relatively strong physical weathering and relatively weak chemical weathering. (2) Environmental variables, including landform, soil type, sunshine duration day(≥3 hours), active accumulated temperature(≥10℃), elevation, and annual evaporation, significantly influenced the spatial distribution of soil particle composition. Variable importance analysis from the random forest model indicated that landform had the greatest influence, contributing over 20% to the model explanation across all soil layers, followed by soil type, which consistently exceeded 10%. (3) In terms of vertical profile distribution, sand content was higher in the 0~25 cm and 25~50 cm layers within the Tarim Basin (central Taklimakan Desert) but lower in the surrounding annular piedmont zone. In the 50~75 cm and 75~100 cm layers, sand content decreased in the central desert area, while the West Kunlun Mountains maintained high sand content throughout all layers. The silt and clay contents in the 0~25 cm and 25~50 cm layers were lower in the desert area than in the surrounding annular piedmont zone, with the opposite pattern observed in the 50~75 cm and 75~100 cm layers. (4) On a macro scale, the spatial distribution characteristics of soil particle composition are controlled by the annular geomorphological pattern of “a basin flanked by two mountain ranges”. This geomorphological pattern influenced the spatial distribution of environmental factors such as soil parent material, soil type, and climate, which consequently governs the spatial distribution of soil particle composition.【Conclusion】 This study provides a scientific basis for the precise management and sustainable utilization of soil resources in the Tarim River Basin, offering support for ensuring the sustainable development of oasis agriculture and ecological environment construction.