Nano-SiO 2 /polypropylene composite was prepared by melt-blending process.The nano-SiO 2 particles were organized by wet process surface treatment with silane coupling agent KH-570.The effect of mass fraction of nano-SiO 2 particles and dosage of KH-570 on the toughening and strengthening of PP matrix were investigated based on the fractography of impact notch and the analysis of crystal structure by X-ray and dispersive structure of nano-SiO 2 by TEM.Results show that the impact and flexural strength and modulus of the composite are improved obviously with low loading of nano-SiO 2 (3 wt%-5 wt%),and the izod impact strength of PP increases twice with 4 wt%nano-SiO 2 .The nano-SiO 2 particles treated can disperse into the matrix resin,which has evident heterogeneous nucleation effects on the crystallization of PP.The optimal toughening and strengthening effects of PP matrix can be obtained when the content of nano-SiO 2 and KH-570 are 4 wt%and 3 wt%,respectively. Nano-SiO 2 / polypropylene composite was prepared by melt-blending process. The nano-SiO 2 particles were organized by wet process surface treatment with silane coupling agent KH-570. The effect of mass fraction of nano-SiO 2 particles and dosage of KH-570 on the toughening and strengthening of PP matrix were investigated based on the fractography of impact notch and the analysis of crystal structure by X-ray and dispersive structure of nano-SiO2 by TEM. Results show that the impact and flexural strength and modulus of the composite are improved obviously with low loading of nano-SiO 2 (3 wt% -5 wt%), and the izod impact strength of PP increases twice with 4 wt% nano-SiO 2 .The nano-SiO 2 particles treated can disperse into the matrix resin, which has evident heterogeneous nucleation effects on the crystallization of PP. The optimal toughening and strengthening effects of PP matrix can be obtained when the content of nano-SiO 2 and KH-570 are 4 wt% and 3 wt %, respectively.