In this paper, SrTiO3 and TiN-decorated SrTiO3 nano composites were successfully prepared via a moderate hydrothermal and calcination process. The resulting SrTiO3-TiN nanocomposites are characterized by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. UV-visible diffuse reflectance spectroscopy is used to investigate the optical properties and the results demonstrate the extension of spectral responses from ultraviolet to visible light region. Compared to pure SrTiO3, SrTiO3-TiN composites reveal obvious enhancement in adsorption and photocatalytic ability. STON samples with TiN-decorated 6 wt % and calcination temperature 250 degrees C, 30 min exhibited highest photocatalytic activity, which could remove 72% of MB within 150 min. This work indicates that other photocatalytic nanocomposites could be exploited by this composite method and TiN may be one kind of materials used for photocatalyts to enlarge their response range of solar light and selective adsorption of different dyes.