Crystallization behaviors and kinetics of iPP were studied in the in-situ prepared isotactic polypropylene/graphene(iPP/G)composites.It was found that the crystallization morphology,crystallization rate and kinetics were significantly influenced by the presence of graphene.Nucleation and epitaxial growth of iPP on the graphene surfaces were observed and studied in detail.It was observed that the nucleation of iPP favored to occur at the wrinkles and edges compared to the smooth surfaces,which was due to a good match of the lattice parameters and the weak spatial hindrance at these regions.Meanwhile,the size of the crystals was decreased because of the numerous nuclei located.The schematic diagram was proposed for the nucleation and growth process of iPP on the graphene surfaces in the iPP/G composites.