Abstract: Polypropylene(PP)/montmorillonite(MMT) nanocomposite was modified by using polypropylene-graft-maleic anhydride(PP-g-MA) as melting blending.The effect of the weight content of PP-g-MA on the melting index, tensile strength, impact strength, thermal property, crystal morphology and dispersion of MMT, was investigaed.It revealed that when adding 5% mass percent of PP-gMA, the crystals size of PP decreased and the dispersibility of MMT in PP matrix was improved, which considerably increased the impact strength of the nanocomposite while keeping the tensile strength unchanged.