Abstract: Soil-Rock mixture(S-RM) is a kind of inhomogeneous geomaterial. Taking a Yunnan highway S-RM slope as an example, horizontal push-shear tests under loading and unloading conditions were preformed to three selected samples. Then the curves of shearing strength versus displacement of these three samples were received. Studies were performed to the characteristics of these curves. Through the analysis of the samples' sliding surface under three-dimension, it seems that it is inaccurately to calculate the strength parameters of S-RM for the scrambling of the three-dimension sliding surface. Based on the three limit-equilibrium theory, the method of calculating the strength parameters of S-RM under three-dimension condition were put forward. Using this method, the strength parameters and the residual strength parameters of S-RM in the study area were received. These parameters can be very important to evaluate slopes.