The linear epoxy-aminopropyltriethoxysilane addition polymer is used as a new epoxy modifier in this paper. The flexural properties and fracture toughness of materials were measured. The experimental results show that copolymer modifier can effectively improve the toughness of resins without sacrificing the stiffness and strength. The properties of epoxy resin blended with aminopropyltriethoxysilane (γ-APS) are also carried out simultaneously as a comparison.