Abstract: The fractal characteristics of particle size distribution of soil-rock mixtures in the right bank of Long-pan in Tiger-Leaping Gorge area are studied by using fractal geometry theory.The quantitative equations reflecting the relationship between particle size average and fractal dimensions are established.It is found that the statistical self-similarity of particle size distribution exists in the soil-rock mixtures.For the soil-rock mixtures is poorly graded,the fractal curve shows special double fractal dimensions,which has relations with the origin and formation of the soil-rock mixtures.