Aiming at the test results of shear band angle under plane strain conditions for anisotropy sand, a comparative analysis was carried out based on the three traditional theories and bifurcation theory. The results of shear band under plane strain condition described by the three traditional theories showed the traditional theories could estimate the minimum, middle and maximum values of the shear band angle of sand, whilst it could not t explain the anisotropy behaviors of shear band. The shear band under the plane strain conditions was easily observed, and it induced shear bands that reduced material strength when the directions of shear band and sand deposition were the same. It resulted in the different anisotropy characteristics in the conventional triaxial conditions and plane strain conditions. Such different characteristics could be explained using bifurcation theory together with anisotropy model. With the direction variation of sand deposition, the model ccould explain the monotonic behaviors of shear angled under conventional triaxial condition from microscopic viewpoint, the bifurcation theory combined with the model could describe the behavior of shear angled under plane strain condition which decreased first and then increased. The comparative analysis of four theories showed that bifurcation theory together with anisotropic model well explained the different shear properties between plane strain and conventional triaxial under various stress conditions, and one could well explain it from the microscopic viewpoint.