This study selected three typical vegetation types—Populus euphratica, Tamarix ramosissima, and Phragmites australis—along with bare sandy land (CK) in the lower reaches of the Tarim River. Surface soil samples (0-10 cm) were collected, and Particle size composition was analyzed using a laser diffraction particle size analyzer.The fractal dimension and correlation analysis methods were employed to examine the particle size distribution and fractal dimension characteristics. The results showed that: (1) Soil particle composition was dominated by fine sand and medium sand, accounting for 67.43% to 91.25% of the total soil content. (2) Vegetation type significantly influenced soil particle size distribution and fractal dimension. Compared with CK, vegetation cover significantly increased the contents of clay and silt, while decreasing the mean particle size. The fractal dimension values followed the order: Populus euphratica (2.58) > Tamarix ramosissima (2.56) > Phragmites australis (2.47) > CK (2.21), with significant differences among them (P<0.05). (3) Clay and silt contents showed an extremely significant positive correlation with fractal dimension(P<0.01), while sand content showed a significant negative correlation (P<0.05).In summary, different vegetation types regulate soil particle composition and fractal structure through distinct ecological effects, thus improving soil texture. Among them, Populus euphratica is the most prominent in promoting fine particle retention and optimizing soil structure. This study demonstrates that soil fractal dimension may act as an integrated quantitative index for assessing the sand-fixing and soil amelioration functions of vegetation in arid regions.