Dumbbell type amphiphilic block copolymers, two polymeric globules connected with poly(ethylene glycol) 2000 or 4000 (PEG 2k, PEG 4k), were synthesized and characterized. The outer polystyrene globules are hyperbranched poly(chloromethyl styrene) synthesized via atom transfer radical polymerization. The degree of branch of the hyperbranched polymer tells that the structure is rather closer to a dendrimer than a general hyperbranched polymer. The synthesized polymers have well controlled structures. The molecular weights and its distributions were chatacterized by GPC and 1H-NMR. The synthesized polymers were micellized in water using dialysis method and critical micelle concentration was measured using pyrene fluorescence method.