A new kind of macroinitiator for nitroxide-mediated polymerization was synthesized via the atom transfer radical copolymerization of styrene (St) or methyl methacrylate (MMA) with vinyl monomer containing nitroxide group．In order to gain the macroinitiator having n side nitroxide groups

the molar ratio of free radical initiator to the monomer containing nitroxide group should be at (n+1)／n in the ATRP system．The optimum conditions of atom transfer radical copolymerization between the St or MMA and vinyl monomer containing nitroxide group were studied in detail and the polymerization mechanism was discussed. The structure of the macroinitiator was also characterized by means of 1H-NMR．