Abstract: Soil particle size distributions in the 0-15 cm soil layer were analyzed in a two-factor (experimental trampling and simulated precipitation) controlled field experiment of 16 treatment combinations. The characteristics of soil particle size distributions were reflected in progressively coarser textured soils from low to high trampling intensities. Precipitation also regulates the process of soil particle size formation. The fractal dimension of soil particles were calculated using a fractal model and soil particle size distribution was negatively correlated with trampling intensity. However, reduced average fractal dimension size was related to precipitation. In a precipitation sequence of dry, natural precipitation, moderate rainfall, and abundant rainfall, the fractal dimension values declined in the sequence 4.33%, 2.61%, 1.34%, and 1.23 respectively. Fractal dimension values were determined by the interaction between precipitation and trampling. Because of high fractal dimension values, soils are susceptible to grazing-induced erosion, and could become desertified if not properly managed. Calculation of fractal dimension is a reliable indicator in monitoring grazing-induced erosion processes and predicting desertification. Therefore, soil fractal dimension measurement could be meaningful for evaluating grazing-induced erosion and the formation of desertification processes.