Abstract: Living"/controlled radical polymerization of styrene initiated by benzyl chloride has been achieved by atom transfer radical polymerization (ATRP) catalyzed by iron dichloride tetrahydrate triphenyl phosphine complexes at 120 ℃. When n (Fe) to n (P) is 1∶3, the polymer number average molecular weight ( M n) increases linearly with monomer conversion. If n (Fe) to n (P) is 1∶2 or 1∶4, the linear relation of M n to conversion does not exist, indicating that there exist many active centers in the polymerization.