The dye molecule Rhodamine-B was used to hydrophobically modify the core-shell Fe3O4@SiO2 nanoparticles, and the modified nanoparticles were used as stabilizer to prepare Pickering emulsions. The modified Fe3O4@SiO2 nanoparticles and Pickering emulsions were characterized and investigated by Zeta potential, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), contact angle measurement, optical microscope and conductivity measurement. The results showed that the mono-disperse nanoparticles with particle diameter 150 nm were synthesized successfully. Rhodamine-B was successfully modified to the surface of Fe3O4@SiO2 nanoparticles and the contact angle increases from 30? to 120?. And the concentration of emulsifier particles has great effects on the stability of the emulsions. Moreover, the stability of emulsions can be modulated by applying a magnetic field.