Electrophoretic polymer coated inorganic pigment were synthesized by using silane coupling agent and highly hydrophilic monomers. Silane coupling agents which have charge and polymerable functional group were used to modify particles and monomers which have more than eight carbon atoms were used to form polymer coating layer on particles by radical reaction. Silane coupling agent serve pigment with charge, and polymer layer reduces the specific density of pigment and prevent the pigment from flocculating in electrophoretic solvent. By choosing proper silane coupling agent and coating monomer, the charge polarity of particles can be control and the final polymer coated pigment show good stability, quick response and high reflectance in electrophoretic image display.