A nanocomposite material was prepared by in-situ intercalation polymerization of VCM directly intercalating into montmorrillonites.The structure of obtained composites was characterized by using small angle X-ray diffration(XRD),scanning electronic microscopy(SEM) and electron probe technique.The results showed that the PVC-montmorrillonite(MMT) composite prepared by in -situ intercalation polymerization was an exfoliated nanocomposite.