The inhomogeneity of the cooling rate and shear rate during polymer processing such as injection molding usually leads to the harvest of a layered structure, which is often difficult to tune. By introducing oscillation shear flow during the packing stage of an injection molding cycle, special injection-molded polylactide (PLA) parts with different thicknesses and crystallinity of skin layers were fabricated via controlling shear durations and oscillation frequencies, as revealed by microbeam wide-angle X-ray diffraction results. For the part of the 2000 mu m thick layer with 50% crystallinity, the heat distortion temperature and Vicat Softening temperature reach 96:6 and 159.3 degrees C, respectively. Moreover, the Young's modulus rises remarkably with the increase of thickness and crystallinity. Significantly, the maximal shear rate appeared 850 mu m from the surface, about 1068 s(-1) (up to 103 s(-1)), which plays a crucial role-for the formation of oriented crystalline morphology.