Amphiphilic magnetic polymer microspheres were synthesized by copolymerization of styrene with poly(ethylene oxide) macromonomer(MPEO)in the presence of Fe3O4 magnetic fluid in ethanol／water medium．The effect of MPEO concentration on the average size of magnetic microspheres was investigated．Magnetic microspheres size

morphology and surface roughness were characterized by scanning electron microscopy and atomic force microscopy．The structure of copolymer was determined by infrared spectroscopy．With increasing poly(ethylene oxide) macromonomer used in polymerization

the surface roughness of microspheres increases．Magnetic microspheres containing 0.4～3.5 mg／g hydroxyl groups could be prepared by varying concentration of MPEO．