The SrTiO3 photocatalyst is successfully prepared by three different routes including a sol–gel method, a acrylamide gel method, and a hydrothermal synthesis method. Phase structure and FTIR analysis indicate that the phase purity and crystallinity of the SrTiO3 photocatalyst are strongly dependent on the synthetic route. The carbonate ion and C–C-stretching vibration peak decorated SrTiO3 oxides improved the surface morphology, BET specific surface area, optical, and electrochemical properties and photocatalytic activity of the SrTiO3 photocatalyst significantly. Photocatalytic experiments indicate that the carbonate ion and C–C-stretching vibration peak decorated SrTiO3 oxides exhibits highest photocatalytic activity for degradation of the congo red dye under simulated sunlight irradiation. The effects of dye concentration, catalyst concentration, and pH value on the photocatalytic activity of the carbonate ion and C–C-stretching vibration peak decorated SrTiO3 oxides were systematically investigated. The excellent photocatalytic activity for the carbonate ion and C–C-stretching vibration peak decorated SrTiO3 oxides can be ascribed to the low recombination and high charge separation due to the synergistic effect of the carbonate ion and the C–C-stretching vibration peak.