In this article, the electrorheological (ER) suspensions containing polypyrrole particles in silicon oil are prepared. These suspensions’ ER properties, in particular their conductive property and the influencing factors, such as particle conductivity, field strength, concentration and shear rate, are investigated experimentally. The results show that the suspension can display significant ER effects only when the particle conductivity is within a certain range, and the suspension’s ER effect increases with particle concentration and field strength, but decreases with the increasing shear rate. The suspension’s current density increases with particle concentration, particle conductivity and field strength, while decreases with shear rate.