Taking advantage of cheap raw materials, polyaniline/octa-(aminopropylsilsesquioxane) (PANI/POSS-NH2) composites with hierarchical structures were obtained by a simple and low-cost method of mechanical agitation combined with sonication. The structure, morphology and electrochemical property of PANI/POSS-NH2 were characterized by nuclear magnetic resonance (NMR), X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammogram (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). Compared with pure PANI, PANI/POSS-NH2 exhibited good specific capacitance, due to the high specific surface area of POSS-NH2 and synergetic effects of the two components. Moreover, POSS-NH2 played an important role in improving the cycling stability of PANI/POSS-NH2.