The particle size distribution of sediment reflects the basic information of soil erosion. Researching the characteristics of sediment separation will improve better understanding to the process and mechanism of soil erosion on the slope. Field scouring experiments were conducted in four different shrub-grass patterns at three different flow rates (15 L/min, 20 L/min and 30 L/min) on the 8° slope in the Pisha sandstone area. This study taken the shrub grassland on the upper slope (SU), shrub grassland on the middle slope (SM), shrub grassland on the lower slope (SL) and grassland without shrub (GL) as the research objects, and bare land was taken as contrast in the Pisha sandstone area. The results showed that:(1) Vegetation could affect the distribution of sediment particles by affecting the hydrodynamic parameters. The sediment particles in different vegetation patterns tended to coarsen with the increasing of scouring time and flow. Silt and sand were the main particles of erosion sediment in this area. (2) The flow shear force, flow power and unit flow power all were negatively correlated with sediment D_V, and positively correlated with D₀ and D₁.The mean D_V of sediment was 2.422, 2.381 and 2.348 under three flow rates, respectively. The D_V under different vegetation patterns followed the order of GLD₀ and D₁ wasopposite to D_V. (3) The relationship between fractal dimension of sediment and hydrodynamic parameters could be described by exponential function and logarithmic function. Regression analysis showed that flow power was the best hydrodynamic parameter for describing sediment distribution characteristics, and using flow power and unit flow power could better simulate the sediment separation characteristics on slope of Pisha sandstone area. This study provided a theoretical basis for further improvement of soil erosion model on slope in Pisha sandstone area in the future.