. Fe3O4 nanoparticles were synthesized and doped into two glass systems (Na2O-B2O3 glass and PbO-Bi2O3-B2O3-GeO2 glasses) at low concentrations using traditional glass melting method. The formation of Fe3O4 nanoparticles was obtained through coprecipitation of Fe(II) and Fe(III) in alkaline media.The size of the Fe3O4 nanoparticles was observed to be around 15 nm. The structure and properties of doped glasses were studied by X-ray diffraction (XRD), scanning electric microscope (SEM), UV-VIS spectray, FT-IR spectray analysis and Faraday rotation test. Compared to the host glass, Fe3O4 nanoparticles doped glasses shown enhanced Faraday Effect in term of Verdet constant and will have potential application in magneto-optical devices.