Abstract: Core-shell st ructured acrylate impact modifier (AIM) particles of poly ( butyl acrylate) graf ted poly(methyl methacrylate) ( PBA-g-PMMA) were synthesized, which were used to prepare AIM/ PVC blends by melting process. AIM particles dist ribution and it s cavitations in PVC resin, the f racture and brittle-ductile t ransition ofAIM/ PVC blends were investigated. The result s show that spherical AIM particles well disperse in the PVC mat rixand toughen the PVC resin effectively. The impact test samples with 615 % (mass f raction) AIM modifiers broke inductile failure. It was found that cavitations are formed in the st ress-whitened area near the fracture surface. Thetoughening mechanism of PVC is synergistic toughening by cavitations of the rubber particles and shear yielding ofthe mat rix.