Based on fractal theory, the fractal characteristics of soil particle size distributions (PSDs) within 0-200 cm soil profiles of the typical vegetation types in Wuliwan Watershed on the Loess Hilly Region were studied to explore the effects of vegetation type and soil depth on soil structure and to explore the relations between the volume fractal dimension and the contents of soil organic carbon, total nitrogen and soil water. The results showed that soil particle composition was mainly fine particles (clay and silt), and silt particles approximately accounted for 56.82%-71.99% of the total volume. The average volume fractions of fine particles were 78.86% and 65.77% for soil profile of Artemisia sacrorum grassland and woodland, respectively. The fractal dimensions of soil PSDs in five typical vegetation types ranged from 2.498-2.599, and most of them increased with the depth of soil layer. At the same soil layer, the fractal dimension of soil PSD showed the following order: Artemisia sacrorum grassland> Astragalus membranaceus grassland>farmland>shrubland>woodland, But there was no significant difference between shrubland and farmland. The fractal dimension of soil PSD in typical vegetation had extremely significant positive correlation with water content and the volume percentage of clay and silt (P<0.01), but significantly negative correlation with the volume percentage of sand and soil organic carbon content (P<0.05).