Abstract: Many usual phenomena in the realm of geology can be seen as strain localization. Ductile shearing bands are shearing strain localization bands. In the first time, a theoretical study on ductile shearing bands based upon strain gradient plasticity theory is conducted in this paper. The regularities of the shear strain and the ratio of shear strain in the shearing bands are got. The theoretical formulas about the displacement of the shearing bands in the two perpendicular directions are obtained. Besides, the regularities of the volumetric strain and the ratio of volumetric strain in the shearing bands are also got. The strain localization causes volumetric strain localization and the localization of porosity factor. If the strain softening intensifies, the shear strain and the volumetric strain localization intensify. Along with the increase of absolute ratio of shear stress, the intensive extent of ratio of shear strain and volumetric strain intensifies.