The dispersion polymerization of St with PEO marcomonomer was successfully carried out with microwave irradiation．The morphology of the PSt-g-PEO mierospheres was characterized by TEM．The results showed that microspheres were spherical in shape with narrow distributions．The effects of St concentration

PEO macromonomer concentration．AIBN concentration

water content in the solvent and microwave power on the sizes of the PSt—g—PEO microspheres were investigated by Photon correlation spectroscopy(PCS)．Under the same microwave power

the sizes of the micrespheres were increased with increasing the initial St concentration and AIBN concentration；when the PEO macromonomer concentration and the water content in the solvent were higher

the smaller mierospheres could be prepared．For the same component ratio

the PSt-g—PEO microspheres prepared under microwave irradiation of 130 W were smaller than those prepared with irradiation of 195 W．