Abstract: The TiO₂-g-C₃N₄ composites were prepared by a uniform precipitation method and the structure and morphology were characterized for g-C₃N₄ and TiO₂-g-C₃N₄ composites by XRD and SEM. The photocatalytic activity of the as-prepared sample was evaluated by degradation of methyl orange under simulated sunlight. The composites with high catalytic performance were combined with the cement stone surface to obtain the photocatalytic cement stone. The results show that the TiO₂-g-C₃N₄ composites prepared at 300℃ and 400℃ have strong heterojunctions, and N-doped TiO₂ was produced at 500℃. The best photocatalytic activity of TiO₂-g-C₃N₄ composites was obtained at 400℃, and the degradation rate reaches 91% under the simulated sunlight for 60 min. By fitting calculation, it is found that the photocatalytic rate of TiO₂-g-C₃N₄ composites obtained at 400℃ is the fastest. The cement stone combined with the TiO₂-g-C₃N₄ composites obtained at 400℃ still have good catalytic degradation performance, and the degradation rate can reach more than 90% under the simulated sunlight for 240 minutes. The TiO₂-g-C₃N₄ composites can reduce the initial setting and final setting time of the cement stone at 400°C and improve its compressive strength.