Electrorheological (ER) fluid is a kind of smart materials that has great potential to be widely used in mechatronics. In this paper, ER fluids were fabricated by dispersing oxalate group-modified amorphous titanium oxide nanoparticles in dimethyl silicone oil with different kinematic viscosities. Their yield stress, zero-field viscosity, ER efficiency, response time, and sedimentation stability were tested. The results indicated that the ER fluid with the silicone oil with a viscosity of 50 cSt presents the optimal ER efficiency, and the fluid based on the silicone oil with a viscosity of 100 cSt shows the shortest response time and good sedimentation stability.