In this paper, polypropylene (PP) and poly (ethylene-co-octene) (POE) as well as PP and PP/POE blends (PP/PPPOE) were fabricated into alternating multilayered materials to improve the toughness of PP efficiently, compared with conventional PP/POE blends. POM, SEM, Micro-polarized FTIR and part-impact test were performed to characterize and investigate the alternating multilayered microstructure and its relationship with mechanical properties. The results showed that the unique content distribution of POE phase, interfaces delaminations, craze deflection, larger subcritical damage zone due to the existence of alternating multilayered microstructure can lead to the great enhancement of toughness of the PP matrix. Moreover, the rigidity of alternating multilayered materials was kept very well due to the existence of the rigid PP layer, indicating that alternating multilayered microstructure was very helpful to keep a good balance between toughness and rigidity. Keywords: Alternating multilayered microstructure; toughness; PP; POE; Toughening mechanism.