With wet surface modification of kaolinite, composite of PP/Kaolinite/PP-g-MAH was prepared by melt blending process. The kaolinite and composite were characterized by means of Flourier transform infrared (FTIR) spectroscopy, thermo gravimetric analyzer (TGA), X-ray diffraction (XRD) and scanning electron microscope (SEM), and mechanical, thermal performance test. The results indicated that the modifier reacted well with kaolinite and produced synergistic effect well with PP-g-MAH. The tensile strength increased by 10.6%, notched impact strength was better than unmodified kaolinite composite. XRD showed that the diffraction peaks of the composite didn’t change evidently, and kaolinite had heterogeneous nucleation effect and increased the degree of crystallization greatly. The heat distortion temperature of the composite was increased by 18 ℃. SEM analysis showed that the modified kaolinite particles were homogeneously dispersed in the PP matrix, and the modification effect of kaolin was increased.