A new effecient catalyst system(FeCl3／2PPh3) for the“living”／controlled radical polymerization of butyl methacrylate by a reverse ATRP process was reported in this paper．With the presence of this catalyst system

the number-average molecular weights of the obtained polymer increased in direct proportion with monom conversion

and the MWDs (molecular weight disctributions) were narrow throughout the reactions(1.17＜Mw／Mn＜1.22). This reaction system did not include the conventional initiators which were used to generate the primary radicals.