In this article, the electrorheological (ER) properties of the suspensions containing dihydroxypropyl chitosan particles in silicon oil with glycerin as activator are reported. In particular, the conductive property of these suspensions and its influencing factors, such as activator content, field strength, concentration, and shear rate, are investigated experimentally. The experimental results show that the suspension can display significant ER effects under the applied electric field strength. An optimum activator content exists, and the suspension＇s current density increases with particle concentration, activator content, and field strength, while it decreases with shear rate.