Highly dispersed SiO2@Fe3O4@C core-shell nanoparticles with controllable particle sizes were prepared. Under electric field, the optical properties of SiO2@Fe3O4@C nanoparticle suspensions of different size, different concentrations, different the solvent was studied, and the results show that the reflection spectrum of 150 nm SiO2@Fe3O4@C nanoparticles at a concentration of 10%(mass fraction) obtain the widest tunable range from 735 nm to 540 nm. With increasing concentration of nanoparticle suspension, the overall reflectance spectra blue shift. The solvent dependence of the electric field-responsive photonic crystals by dispersing 150 nm particles into different solvents was investigated, and the results show that the greater refractive index, the greater the reflection wavelength. The response time of the suspensions is 150 ms, and the suspensions have recovery after electric field disappeared.