A visible-light activated photocatalyst N-doped TiO2 nanocrystalline was synthesized via sonochemical method at low temperature. The N-doped anatase TiO2 nanoparticles were prapared by sonication of the solution of tetrabutyl titanium and ammonium in water and ethanol at 70 °C for 150 min. The crystalline forms and crystallite sizes of the as-prepared sample is characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and UV-Visible absorption spectrum.The product structure was dependent upon the reaction temperature and reaction time. The photocatalytic activity of the as-prepared photocatalyst was evaluated via the photodegradation of a basic dye methyl violet. The results show that the N-doped TiO2 nanocrystalline prepared by sonication has an excellent photocatalytic activity under UV light and simulated sunlight.