KH-550 modified nano-TiO2/RGO composites were synthesized via a one-step hydrothermal method to improve the photocatalytic activity of nano-TiO2.The composites were characterized by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Raman spectra, X-ray Photoelectron Spectroscopy (XPS). In addition, methyl orange solution was used in optical degradation to investigate the photocatalytic properties. The results showed that the photocatalytic degradation rate of KH-550 modified nano-TiO2/RGO composites was 57.32% while pure nano-TiO2, nano-TiO2/RGO was only degraded 28.83%, 46.68% during the same time and same mass ratio. Compared with nano- TiO2, the photocatalytic degradation rate of nano-TiO2/RGO and KH-550 modified nano-TiO2/ RGO composites were improved by 17.85%, 28.49% respectively. However, the composites displayed the best photocatalytic performance when the mass ratio of graphene and KH-550 modified nano-TiO2 was 8%.