Theoretical calculation shows that electrorheological fluids with dielectric coating conductive particles as a dispersed phase will give high shear stress. We has coated graphite particles with TiO2 using sol-gel technique. Rutile phase TiO2 coating graphite composite particles have been got. The shear stress of composite particles/silicone oil electrorheological fluid is one order higher than that of the TiO2/silicone oil. When the electric field strength is 1.7kV/mm, the shear stress of composite particles/silicone oil electrorheological fluid reaches 1.25kPa， and electric current density is less than 10μA/cm2.