In this paper, we synthesized nanosized silica/titanium zeolite/titanium oxide (TS-1/TiO2) core/shell nanocomposite particles using nanometer-scale TS-1 as templates, and the electrorheological (ER) properties under various external electric field strengths were studied. The morphology, crystal structure, chemical state, and ER behavior of TS-1/TiO2 core/shell nanoparticles were studied by several characterizations, for example, X-ray diffractometry, transmission electron microscopy, scanning electron microscopy, Fourier-transform infrared spectroscopy, the thermogravimetric analysis, X-ray photoelectron spectroscopy, and ER measurements. The shear stress and viscosity, yield stress, switching effect, and dielectric properties of as-obtained ER fluids were analyzed by measuring the ER effect under different electric field intensities. Finally, we found that the composite particles have an excellent ER effect and are a promising ER material.