In order to meet the growing demand for large-scale energy storage, low-cost sodium-based aqueous capacitor battery has received people's attention. Polypyrrole is an inexpensive conductive polymer. In this paper, polypyrrole nanowires with anionic structure were prepared by chemical oxidation and doping ions during the preparation. They could be used as negative electrode material for sodium ion capacitor cells.The sodium ion storage mechanism of polypyrrole doped with anions was studied by cyclic voltammetry, AC impedance method and constant current charge-discharge method. Morphology and structure were analyzed by X-ray diffraction, infrared spectroscopy and scanning electron microscopy. Anions doped polypyrrole can reach a steady capacity of 200 mAh / g in 1 mol / L NaNO₃ solution. After 500 cycles, the capacity retention is 70% at a current density of 0.1 A / g.The specific capacity of 120 mAh / g can still be achieved at a current density of 5 A / g. The polypyrrole doped with ions has two kinds of sodium ion intercalation mechanism, has the advantages of batteries and capacitors, has a larger capacity and excellent rate performance, good cycle performance.