In this paper, taking elastic and plastic characteristics of rock into account, the authors have studied the relationship between different constitutive models. By transforming material parameters merely, on the basis of Equivalent Mohr-Coulomb Yield Criterion, the researchers achieved the application of these relationship in the computer program-Ansys5.7. They also have discussed the magnitude relationship between the transformed parameters and the original ones. By analyzing the cases of rock slope with obvious sliding surface, the researchers proved that it is liable to replace Mohr-Coulomb Yield Criterion with Equivalent Mohr-Coulomb Yield Criterion. We can use Equivalent Mohr-Coulomb Yield Criterion to simulate rock material, the results are smaller and more conservative than the standard ones. Meanwhile, the authors indicate that it is beneficial to apply Equivalent Mohr-Coulomb Yield Criterion to simulate rock material in rock slope projects with obvious sliding surface which have accurate standard requirements about displacement.