Abstract: In recent years, semiconductor photocatalysis technology as a fast-developing environmental technology, has great application prospects in degradation of pollutants in water and production of renewable clean energy. In this paper, Ag-modified Ag-Ag₂O/TiO₂-graphitic carbon nitride (g-C₃N₄) heterojunction composites, which were based on the prepared 20 wt%g-C₃N₄/TiO₂ composites, were successfully synthesized by partially oxidizing nano-Ag particles during the hydrothermal process. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence spectroscopy (PL) and transient photocurrent analytical tests were used to characterize and analyze the crystal structure, morphology and optical properties of Ag-Ag₂O/TiO₂-g-C₃N₄ photocatalysts. The photocatalytic activity of the Ag-Ag₂O/TiO₂-g-C₃N₄ was also investigated through degradation of methylene blue (MB) under visible light irradiation. It is found that Ag is partially oxidized to Ag₂O, and their synergistic effects with g-C₃N₄ make the Ag-Ag₂O/TiO₂-g-C₃N₄ composites have good visible light photocatalytic activity. After 4 h of visible light irradiation, the degradation rate of MB by the Ag-Ag₂O/TiO₂-g-C₃N₄ photocatalyst is close to 50%.