Abstract: Based on the criterion of spatial mobilization plane (SMP), the relationship among the six principal stress spatial domains of the octahedral surface, the SMP and stress state is studied. Considering that the SMP of the soil material changes with the angle of the principal stress, a mathematical expression is proposed to reflect the strength characteristics of anisotropic materials under general stress conditions. The simulated results of the strength characteristics of anisotropic loess under true triaxial conditions show that the established expression for the variation of anisotropic strength variation based on variation of spatial plane can better reflect the strength variation law of loess materials under general stress conditions, especially the strength variation when the direction of the SMP of materials is at an arbitrary angle to the principal axis of stress.