Abstract: Nano-SiO₂ was firstly modified by coating with ethylene-methyl acrylate-glycidyl methacrylate (E-MA-GMA) elastomer through the direct solvent process，and the dispersion of nano-SiO₂ in PBT and the effects of modified nano-SiO₂ on the properties of PBT were investigated. FTIR，TEM and SEM results indicate that the epoxy group of E-MA-GMA can react with the hydroxyl groups of the silica surface to destroy the aggregation of SiO₂ and reduce the interactions between the nano-SiO₂ particles；SEM results show that the mass ratios of 10%～20% E-MA-GMA can improve the dispersion of nano-SiO₂ in PBT and the interfacial adhesion between the two phases，and thus the flexural properties and tensile strength of nano-SiO₂/PBT composite are increased. The incorporation of E-MA-GMA modified SiO₂ particles increases the tensile strength，flexural strength and flexural modulus by 9%，14% and 20% higher than those of pure PBT respectively.