Atactic polypropylene (aPP) /isotactic polypropylene (iPP) blends with different aPP contents and with desired mechanical properties were prepared through oscillation shear injection molding (OSIM) technique that can impose oscillation shear flow on polymer melts during solidification at the packing stage of injection molding. Although aPP component was reported as a notably adverse factor to the formation of shish-kebabs and the crystallization of iPP, hence the mechanical properties of aPP/iPP blends, our mechanical results show that the addition of aPP has small effect on the OSIM blends’ mechanical properties provided that the aPP content in blend is not more than 30 wt%. For OSIM sample of blend with 30 wt% aPP, the mechanical properties, 52.8 MPa for tensile strength and 13.1 KJ/m2 for impact strength, are still higher than those of CIM pure iPP and show only a little decrease compared to OSIM neat iPP sample, whose tensile strength and impact strength are 58.5 MPa and 19.4 KJ/m2, respectively. Moreover, the mechanical properties of blends increase further with the decrease in aPP content. The hierarchic structure of the injection-molded samples was characterized through wide-angle X-ray diffraction (WAXD), small-angle X-ray scattering (SAXS) and scanning electron microscopy (SEM). It was found that highly orientated inner structure, i.e. shish-kebabs induced by intense shear flow, was successfully obtained. Hence OSIM samples with this structure have a dramatic improvement both in tensile strength and in impact strength, compared with the CIM samples. It is unimaginable before that the aPP/iPP blends still have so high mechanical properties under the case that the aPP content is high up to 30 wt%. Our results open a new field for efficient usage of aPP, a by-product of iPP production, which is always regarded as an industrial waste.