Polystyrene-block-polycarbonate-block-polystyrene was synthesized by atom transfer radical polymerization of styrene using polycarbonate having two 2-bromoisobutyryloxy end groups as the macroinitiator, which was prepared by condensation polymerization of bisphenol A with triphosgene in the presence of chain-stopper, 2-(4-hydroxyphenyl)-2-(4-(2-bromoisobutyryloxy)phenyl)propane. While polycarbonate-graft-polystyrene was synthesized by atom transfer radical polymerization of styrene using polycarbonate having 2-bromoisobutyryloxy side groups as the macroinitiator, which was prepared by condensation of bisphenol A and 1,1-bis(4-hydroxyphenyl)-1-(4-(2-bromoisobutyryloxy)phenyl)ethane with triphosgene. The molecular weights of polystyrene block or graft chains increased linearly with monomer conversion, and their polydispersities were low throughout the blocking or grafting polymerization process.