The invention discloses a preparation method and application of a polypyrrole/titanium dioxide-doped nanotube composite material. In the method, a TiO2 nanotube is taken as a working electrode, a platinum sheet is taken as a pair electrode, a saturated calomel electrode is taken as a reference electrode, an aqueous solution containing sodium p-tolue and pyrrole is taken as electrolyte, the pH value is adjusted to 1 to 2; a layer of polypyrrole film doped with the sodium p-tolue is deposited on the surface of a TiO2 nanotube electrode through an electropolymerization reaction, and the prepared composite material is applied to a sodium ion battery. The prepared doped polypyrrole is firmly combined with the TiO2 nanotube, and the hollow TiO2 nanotube has a large specific surface area, high mechanical strength and high structural stability, and has high stability after being doped with the polypyrrole; a sodium ion transport channel and space are provided; the hollow TiO2 nanotube and the polypyrrole are electrode active materials with energy storage activities, so that the synergetic additive effect between the two components in the composite material are brought into full play, and the charge/discharge specific capacity and cycle stability of the composite material are high; the method is simple and environment-friendly.