The invention discloses a joint shearing whole-process damage constitutive model for determining a yield point based on a stress difference. The method comprises the steps that S1, setting a joint thin-layer microscopic unit body to be loaded and then enters a linear elasticity stage, the joint thin-layer microscopic unit body is an isotropic continuous medium, the microscopic unit body is instantaneously completed when being converted from a lossless state to a lossy state, and the process is irreversible; S2, defining an external load threshold F * based on a Weibull distribution function toobtain a damage probability density function of the mesoscopic unit body; S3, based on a rheological model mechanical element, simulating the load condition of a mesoscopic unit body by adopting thecombination of a spring and a friction plate to obtain a statistical damage constitutive model of the joints under the shearing action; S4, determining an external load threshold F * according to twoparts, namely damage and non-damage, of the rock and soil material after being subjected to load damage, and obtaining a damage evolution model and a joint shear deformation damage constitutive modelof the joint in the shear deformation process; S5, determining parameters m, u0 and us of the joint shear deformation damage constitutive model; and S6, verifying the correctness of the constitutive model.