The micellization of amphiphilic graft copolymer polystyrene-graft-poly(ethylene oxide) (PS-g-PEO) in selective solvent, toluene, was studied by means of H-1-NMR, TEM and viscometry. Micelle formation of PS-g-PEO in toluene was strongly dependent on concentration and temperature. An increase in temperature shifted the micelle formation markedly to lower concentration. The micelle was formatted at certain concentration, and it was spherical structure. The viscosity data were analyzed to estimate the cmc value.