Atom transfer radical polymerization with FeCl2/CH3COOH as the catalyst has been successfully implemented for styrene. Various initiators have been used, among which carbon tetrachloride is the most effective one. High molecular weight products were obtained when CCl4 was used as the initiator, and the measured molecular weight was close to the calculated one. Block copolymerization (PS-b-PMMA) was performed to confirm the living/controlled nature of the polymerization. H-1 NMR was used to characterize the structure of the macromolecular initiator and the block copolymer. If other initiators, such as benzyl bromide, ethyl 2-bromopropionate and alpha -bromoethyl benzene, were used, the polymerization occurred at ambient temperature resulting in oligomer. The molecular weight of the oligomer approaches to 4600 (M-n,M-th = 10000). Thus acetic acid, which is cheaper and less toxicity, can be used as coordinative ligand in ATRP initiated by CCl4 mediated by iron.