Nano-SiO₂ with epoxy functional groups was synthesized by a two-step method. SiO₂/rPET nanocomposites were prepared by melt blending modified SiO₂ with recycled PET. The modified SiO₂, as a heterogeneous nucleation center, promoted the crystallization of polyester; the epoxy groups provided by the organic layer on the inorganic particles were cross-linked with the polyester, which increased the complex viscosity of the recycled PET; also acted as a stress concentration point. Organic layer increased the compatibility of polymers and inorganic particles, and reduced the interaction between inorganic particles. As a result, the nanocomposites reached a balance of rigidity and toughness. The properties of nanocomposites were related to the dispersion of SiO₂. Under experimental conditions, the optimal content of SiO₂ was 1 wt%. The nanoparticles did not agglomerate, and the crystallinity reached 27.45%, which was an increase of 28%; tensile strength and Izod impact strength were 37.13 MPa and 1.60 kJ m^-2, which were increased by 80% and 100%, respectively.