Abstract: PC-ACR blends was prepared by blending polycarbonate (PC) with acrylic copolymer (ACR) which was selfmade. Influence of modifier size and glycidyl methacrylate (GMA) introduced into shell of ACR on impact strength of PCACR blends were investigated. Increasing of notch toughness of PC-ACR which ACR shell had introduced GMA is not effective. Whereas diameter of ACR has great influence on impact toughness of PC-ACR blends. The J integral fracture toughness analysis was applied to compare influence of modifier size with energyabsorption ability of elastic deformation and plastic deformation. Plastic deformation as main energyabsorption routes plays a major role in enhancing toughness of blends. ACR with size of 177.5 nm is found to be mostly effective, which is in accordance with the impact strength acquired from izod impact test.