Abstract: The experiment of photoelastic mechanical model for failure mechanism of slope rock mass shows that the mining operation in the open pit has evident effect on the mechanical state of pit slopes by the action of stress and volume weight of the rock mass. Gelatin was used in the experiment. The model was designed on a scale 1∶1100. The displacement and deformation of the slope rock mass were modeled under the effect of self weight stress and tectonic stress. Then the failure mechanism for deformation of the rock mass by the effect of two stresses are discussed from the experiment result.