Abstract: In order to study the shear mechanism and shear strength component characteristics of soil-rock mixtures, seven groups of graded soil-stone materials are prepared, covering three typical cases of good gradation, uniform particle size and missing intermediate particle size, representing the forms of stone content in the range of 10% to 75%. Under this condition, the construction models for shear strength and gradation-stone content, shear mechanism and shear strength component are studied. It is concluded that the content of coarse particles in soil-stone mixtures is the key factor to determine the strength. The shear strength of soil-rock mixtures is composed of the occlusal component, friction component and fracture component. Through analysis, the friction component accounts for about 10% of the total shear strength, and the theoretical model formula for the occlusion component and friction component is deduced from the shear transport mechanics process from the angle of the micro-motion of particles. The model formula covers the parameters such as stone content, initial contact horizontal angle, internal friction angle and particle size. From the calculation of the model, it is found that the proportion of occlusion and friction components is exponentially positively correlated with the stone content, and the functional expression under the boundary condition is given.