Abstract: Graphene oxide-SiO₂ (GO-SiO₂) hybrid materials were firstly synthesized by using sol-gel method, and then GO-SiO₂/polypropylene (PP) composites were prepared through melting blending. The structures and properties of fillers and GO-SiO₂/PP composites were characterized and investigated by using FTIR, XRD, XPS, DSC, SEM, dynamic thermo-mechanical analysis (DMA), tensile and impact tests. The results show GO has been chemically functionalized. The mechanical property tests verify that GO-SiO₂ has good synergistic effect on strengthening and toughening of PP matrix, and the mechanical properties of GO-SiO₂/PP composites are superior to those of SiO₂/PP and GO/PP composites. When the mass ratio of GO/SiO₂ is 1:1 and the GO-SiO₂ mass fraction is 0.1wt%, the tensile strength and impact strength of GO-SiO₂/PP composites are 38.9 MPa and 7.6 kJ/m², respectively, which increase by 29.4% and 66.3% compared with those of PP matrix. DSC tests show that the melting and crystallization temperature of PP in the GO-SiO₂/PP composites are 167.4℃ and 111.7℃, which increase by 4.7℃ and 5.2℃, respectively, compared with those of the pure PP. DMA tests show that the incorporation of GO-SiO₂ results in increasing of storage modulus and the shifts of loss modulus peaks to higher temperature. SEM observations show that when the addition of a small amount of GO-SiO₂, the filler can be evenly dispersed in the matrix, but aggregation appears at higher GO-SiO₂ mass fraction.