Abstract: Chemical co-precipitation was selected as the preparation methods of magnetic nanoparticles Fe3O4. XRD and TEM pictures showed that Fe3O4 particles obtained were well crystallized cubic particles with high purity. VSM showed that the Fe3O4 nanoparticles were paramagnetic. Further the Fe3O4 /TiO2 composite material, which prepared by means of the homogenous precipitation coating technique, is studied. Its structure and optical properties are characterized by XRD and UV-Vis. The results indicate that TiO2 coating on the surface of Fe3O4 is equable. The Fe3O4 /TiO2 composite material has a large red shift of absorption band edge into the visible light. The absorbance is apparent increase at the same time, which is favorable for the development of daylight catalyst.