Nitrogen doped anatase/rutile/brookite titanium dioxide (N-TiO₂) regular nano-rod bundle photocatalyst for improving visible light photocatalytic activity was prepared through a template-free sol-hydrothermal method. The properties of the materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflectance spectra (UV-Vis DRS), Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Photocatalytic degradation of methyl orange (MO) in an aqueous solution under visible light irradiation was used as a probe reaction to evaluate the photocatalytic activity of the mixed-phase N-TiO₂ nano-rod bundle. The results of characterization combined with photocatalytic activity of MO photodegradation showed that the synergistic effects among N doping, mixed-phase and nano-rod bundle structure were the main reason to improve photocatalytic activity of mixed-phase N-TiO₂ nano-rod bundle compared with P25-TiO₂. The possible mechanism of MO degradation by mixed phase N-TiO₂ nano-rod bundle photocatalyst was preliminarily discussed.