Photocatalytic hydrogen evolution under visible light is of great potential for renewable energy development. In this work, unalloyed Au/PtO nanoparticle (NP) co-modified graphitic carbon nitride (g-C3N4) photocatalyst is fabricated through a simple photodeposition method. The obtained g-C3N4 composites with co-existed Au and PtO cocatalysts exhibit a considerable enhancement in the photocatalytic hydrogen evolution activity and possess good stability during cycling experiments. The optimal Au-PtO/g-C3N4 photocatalyst shows a H2 production rate of 16.9μmolh(-1), which exceeds that of PtO/g-C3N4 and Au/g-C3N4 by a factor of 1.5 and 10.6, respectively. Further characterizations demonstrate that the synergetic action of electron-sink and catalytic effects of PtO along with surface plasmon resonance (SPR) effect of Au NPs, greatly improves the photocatalytic performance of g-C3N4 under visible light. Our study should bring in new insight into the design of effective g-C3N4-based photocatalysts for solar-to-fuel conversion.