A novel amphiphilic macrocyclic graft copolymer with multi-side chains which consists of a hydrophilic poly(ethylene oxide) (PEO) ring and hydrophobic polystyrene (PS) lateral chains was described. These copolymers were synthesized via combination of anionic ring-opening polymerization and nitroxide-mediated radical polymerization (NMRP). The heterofunctional monomer 4-glycidyloxy-2, 2, 6, 6-tetramethylpiperidine-1-oxyl (GTEMPO) was first prepared and copolymerized with ethylene oxide (EO), and a linear α, ω-dihydroxy-poly(ethylene oxide) with pendant TEMPO groups was obtained. The radical polymerization of styrene (St) was performed in the presence of c-PEOT using benzoyl peroxide (BPO) as initiator. the critical micelle concentration (cmc) of c-PEO-g-PS was measured by the common fluorescence probe technique in water using pyrene as the fluorescence probe.