A series of directional shear tests on Qinghai remolded loess under different conditions of average principal stress were performed using the British GDS Hollow Cylindrical Torsion Shear Apparatus. The influence of the average principal stress on the stress-strain characteristics of the Qinghai remolded loess was studied. In the test, the principal stress coefficient remained unchanged. Under different conditions of the average principal stress, the remolded loess samples were subjected to two kinds of shear failure stress paths in which the principal stress axis did not rotate and rotated 45 °. The experimental results show that the average principal stress and the principal stress direction angle have a significant effect on the strength and deformation of the remodeled loess; the octahedral peak shear stress and the average principal stress of the reshaped loess when the major principal stress direction angle is equal to 45° shear failure are linear, and the development trend of the octahedral shear strain generated by the reshaped loess failure is basically the same; during the shearing process, the major and minor strains of the remodeled loess should develop symmetrically, and the median and major strains increase only slightly during failure. When there is no peak in the octahedral shear stress-strain curve, it is recommended to use the octahedral shear stress corresponding to 15% of the octahedral shear strain as the destructive criterion for reshaped loess.