Abstract: Two reactive acrylate triblock copolymers including poly(methyl methacrylate-co-glycidyl methacrylate)-b-poly(butyl acrylate)-b-poly(methyl methacrylate-co-glycidyl methacrylate) (PMGBMG) and poly(methyl methacrylate)-b-poly(butyl acrylate-co-glycidyl methacrylate)-b-poly(methyl methacrylate) (PMBGM) were synthesized via initiator for continuous activator regeneration atom transfer radical polymerization (ICAR-ATRP). Nano-SiO₂ modified by 3-ainopropyltriethoxysilane (KH-550) was grafted on block copolymer to prepare PMGBMG-SiO₂ and PMBGM-SiO₂ as tougheners for epoxy resin. Results show that addition of 5%PMGBMG-SiO₂ in E-51 epoxy resin can increase the critical stress intensity factor (K_IC) by 145% compared with pure epoxy matrix. Meanwhile, the tensile strength and modulus are increased by 8% and 31% respectively, which are superior to the resins modified by pure copolymer and PMBGM-SiO₂. The toughness and rigidity are improved simultaneously, while heat resistance is also well maintained.