Micro power sources are required to be used in autonomous microelectromechanical system (MEMS). In this paper, we designed and fabricated a three dimensional (3D) MEMS supercapacitor, which is consisting of conformal silicon dioxide/titanium/polypyrrole (PPy) layers on silicon substrate. At first, ''through-structure'' was fabricated on the silicon substrate by high-aspect-ratio deep reactive ion etching (DRIE) method, which enlarges the available surface area significantly. Then the SiO2/Ti/PPy layers grew sequentially on the ³through-structure´. Finally, the supercapacitor was investigated by electrochemical methods.