In this work, an Ag2O modified g-C3N4/TiO2 ternary heterogeneous photocatalyst was prepared through simple calcination and efficient hydrothermal synthesis way. The as-prepared composites were analyzed by powder XRD, FT-IR, HRSEM with EDX mapping, HRTEM, XPS, UV-Vis DRS and PL spectra respectively. The Ag2O modified g-C3N4/TiO2 photocatalyst displays a narrower bandgap and improved the RhB dye photo-degradation efficiency was reached at ~94.5% for 60 min under visible light exposure. Also, the reaction rate constant (k) of RhB dye and phenolic impurities degradation efficiencies for g-C3N4/TiO2-Ag2O PCs was 5.8 and 4.97 folds higher than that of pristine g-C3N4. Besides, the g-C3N4/TiO2-Ag2O composite PCs sustained superior photo-degradation performance after the five reusability tests, indicating excellent stability and durability. The excellent photocatalytic performance has been attributed to the synergistic heterostructured formation between Ag/Ag2O among g-C3N4/TiO2 composites, which facilitates the interfacial electron separation/transfer, and great visible-light utilization ability. For experimental results, a possible photo-degradation mechanism was also proposed. Display omitted •Ag2O modified g-C3N4/TiO2 photocatalyst was prepared by hydrothermal synthesis way.•g-C3N4/TiO2-Ag2O displayed 5.8 times superior to g-C3N4 degradation efficiency.•g-C3N4/TiO2-Ag2O catalyst ensured superior degradation process after five recycling.•A possible photo-degradation mechanism was also proposed.•Ag2O SPR effect was deposited on the g-C3N4/TiO2 surface plays an electron bridge.