PANI nanofibers are prepared electrochemically by template-free method on a stainless steel electrode. Both the hydrophilicity and the lipophilicity of the modified SS surface are enhanced by the nanostructured PANI, and a super-amphiphilic surface is obtained in this way. The influence of polymerization conditions, such as polymerization potentials, polymerization time, the acidity, and the dopants on the super-amphiphilic property, has been systematically investigated. In addition, the mechanisms of obtaining a super-amphiphilic surface are briefly discussed.