Abstract: Polypropylene (PP)/poly(ethylene terephthalate) (PET) blends were prepared by a twin-screw extruder, and a singlescrew extruder with different screw construction and high-shearing extrusion die respectively, and effect of extrusion processing methods on their microfibrillar micromorphology was investigated by scanning electron microscopy. The results indicated that only PET particles as a dispersion phase were formed in the PP matrix when processed by the twin-screw or singlescrew extruder with threezone screws. When using the single-screw extruder equipped with a Maddock mixing section screw, some short and thick PET microfibrils were observed. Nevertheless, the microfibrils with a mean diameter of 5 μm and a length (L)/diameter (D) ratio over 20 could be achieved in the PP/PET blends when being melt-extruded with the single-screw extruder, followed by hot stretching and quenching. However, the equipment for this process is too complicated to realize the industrialization. Moreover, using a single-screw extruder equipped with a customdesigned high-shearing extrusion die, the microfibrils with a diameter of 5~7 μm and a L/D ratio over 20 could also be generated in the matrix. This method is facile to be industrialized.