Single-component graphitic carbon nitride (g-C3N4) are faced with inadequate visible light absorption and low quantum efficiency arising from the rapid charge recombination, limiting their efficient photocatalytic degradation of organic pollutant under visible light radiation. Here, we demonstrated a ternary photocatalyst composed of Ag3PO4, graphene oxide (GO), and g-C3N4 synthesized by chemical precipitation method, in which Ag3PO4 as the photosensitizer and GO as the cocatalyst that significantly promoted the photocatalytic activity of g-C3N4 for Rhodamine B (RhB) degradation under visible light radiation. The ternary photocatalysts (Ag3PO4/GO/g-C3N4) exhibited enhanced absorption in the visible region and superior photocatalytic activity compared with single-component or binary composite photocatalysts for RhB degradation. The degradation rate toward RhB could reach to 94.8% under visible light irradiation for 50 min, and we found that it was the hole (h(+)), superoxide radical (O-2(center dot-)) and hydroxyl radical (OH center dot) that played a major role in RhB degradation. Meanwhile, the ternary photocatalyst showed enhanced photocatalytic stability attributing the synergistic effect among them, and the possible mechanism for the enhanced photocatalytic activity and stability was carefully discussed. The present work provides a facile development of a g-C3N4-based ternary photocatalyst system for highly improved photocatalytic activity by coupling a small amount of Ag-based photosensitizer and metal-free GO cocatalyst.