In this paper,Fe3O4@SiO2particles were prepared by chemical co-precipitation method. Oil sodium was added when Fe3O4nuclear growing. Then, TEOS was added to prepare Fe3O4@SiO2 composite nanoparticles and magnetic microspheres. The properties of theFe3O4, Fe3O4@SiO2 composite nanoparticles and Fe3O4@SiO2 composite microspheres were tested by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR). The magnetic properties were studied by vibrating sample magnetometer (VSM). The result shows that the maximum saturation magnetization of Fe3O4@SiO2 microspheres (34.85emu/g) was lower than that of the Fe3O4 powder (79.55emu/g), but obviously higher thanFe3O4@SiO2 nanoparticles, but the residual magnetism and coercivity force of microspheres were obviously enhanced.