Abstract: The method for synthesis of novel magnetic polystyrene microspheres coated with Fe3O4 nanoparticles，for applica- tion in magnetically stabilized fluidized-bed reactors，was investigated.The microspheres were prepared by suspension poly- merization.Morphologies，particle sizes，magnetic properties of the magnetic polystyrene microspheres，and amount of Fe3O4 coated were investigated by scanning electron microscopy（SEM），infrared spectroscopy（FT-IR），magnetic property using vibrating sample magnetometer（V-SM），and thermo gravimetric analysis（TGA）.Results showed that the new type of synthe- sized polystyrene@Fe3O4 magnetic microspheres were porous，spherical in shape with a narrow particle size distribution in the range of 150~200 μm.The amount of Fe3O4 coating reached 7.81%（mass fraction） in nitrogen atmosphere，and the maximum saturation magnetization was 3.97 A·m2/kg at room temperature.

Key words: suspension polymerization, Fe3O4 magnetic nanoparticles, surface modification, coating, magnetic polystyrene microspheres