Smart nanocomposites of the conducting polymers such as polyaniline and polypyrrole with clay were investigated especially for electro-responsive electrorheological (ER) materials. These conducting polymer/clay nanocomposites were prepared via either in-situ polymerization, emulsion polymerization or solvent intercalation as well as pickering emulsion. Internal structure and thermal properties of these nanocomposites were examined via XRD, TEM, and thermogravimetric analyzer. Moreover, their ER behaviors were measured via a rotational rheometer with an external electric field controller. ER fluids based on different conducting polymer/clay nanocomposites demonstrated diverse ER characteristics such as yield stress and flow curve. Typical models were also used to investigate the rheological behaviors of the polymer/clay based ER fluid.