Abstract: Polyaniline was prepared by chemical in-situ polymerization at ambient temperature.The morphology and structure of polyaniline were characterized by scanning electron microscopy（SEM） and X-ray diffraction（XRD）.Symmetric redox supercapacitor was assembled with the PANI as active electrode material and 1 mol/L Na₂SO₄ aqueous solution as electrolyte.The capacitive performances of the supercapacitor were tested with cyclic voltammetry and galvanostatic charge-discharge.The results show that the PANI product has high capacity,good power characteristics and good cycle performance.The specific capacitance of the PANI electrode is about 451 F/g at the charge-discharge current density of 5 mA/cm².After 1000 charge-discharge cycles the specific capacitance of the PANI electrode is about 208 F/g.The specific capacitance of the PANI electrode is about 230 F/g at the charge-discharge current density of 20 mA/cm.Energy density up to 7.35 Wh/kg.