Abstract: The effect of CPEchain structure on the modification of PVCblend has been studied by infrared spcciroscopy (IR), and differential scanning calorimetry (DSC). Dynamic mechanical spectra of the PVC/CPE blends indicate that they are partially compatable two phase systems. The morphology of the PVC/CPE blends were observed by transmission electron microscopy (TEM). High-impact strength of the PVC/CPE alloy is obtained when the rather regular network structure of CPEis formed.