The theory and methods of anisotropic shear yield criterion is studied on the basis of isotropic Mohr-Coulomb yield criterion. The above theory and methods are applied to establish orthotropic shear yield criterion and to analyze the way to introduce it into the numerical analysis. In order to introduce the orthotropic shear yield criterion into FLAC3D
the codes are developed by using the FISH language of FLAC3D. Theoretical analysis and numerical analysis indicate that the orthotropic shear yield criterion is related to 3 principal stresses and the isotropic shear yield criterion is a special case of the orthotropic shear yield criterion. The analysis also shows that the maximum shear stress plane can not be the same of yield plane in orthotropic materials.