Abstract: Monodisperse copolymer microspheres were prepared by dispersion polymerization in ethanel/water medium using polyvinylpyrrolidone (PVP) as a steric stabilizer, 2- (methacryloyl) ethyltrimethy lammonium chloride (MTC) as copolymer monomer and 2, 2-azobisizobutyronitrile (AIBN) as an initiator.The results show that the copolymer structure synthesized was in accordance with the expectable structure.The influencing factors on the copolystyrene microspheres size and size distribution were investigated.The amount of initiator (AIBN) and stability (PVP) influence the size and the distribution of copolymer microspheres.The amount of copolymer monomer (MTC) has little influence on the distribution of copolymer microspheres, but it is in favor of TiO₂ coating.