Aim\ To explore the furthest dosage of coupling agent in polyproplen/SiO\-2(PP/SiO\-2) nanocomposites. Methods\ PP/SiO\-2 nanocomposites are produced by melting blend process and then the best dosage of silicane KH 560 is discussed by analyzing its mechanical behaviors and SEM photo graghs. Results\ The mechanical behaviors of PP/SiO\-2 nanocomposites are optimal when the dosage of silicane KH 560 is 10% of SiO\-2 nanoparticles. Conclusion\ The conventional empirical fomula used to calculate the dosage of micron inorganic silicane can not apply to inorganic nanoparticles.