Abstract: A reduced graphene oxide (RGO)-doped graphite-phase carbon nitride (RGO-g-C₃N₄) was prepared, and then the Pd-Pt alloy nanoparticles were uniformly immobilized on the RGO-g-C₃N₄ (Pd-Pt/RGO-g-C₃N₄), giving rise to supported catalyst. The catalyst was characterized by high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), nitrogen adsorption-desorption, and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The obtained catalyst was then applied to catalyze the selective hydrogenation of benzaldehyde under the irradiation of visible-light. The XRD and the XPS analyses show that small amount doping of RGO or other additives do not change the structure of g-C₃N₄, and the nitrogen adsorption-desorption measurement indicates that small amount doping increases the specific surface area of the support. The HRTEM and the XPS analyses revealed that the noble metals on the support were successfully reduced by the NaBH₄, and the resulting Pd-Pt alloy nanoparticles (NPs) showed a uniform size and were homogeneously distributed on the support. The optimal catalytic conditions for the reaction were investigated by changing the doping amount of RGO, the doping types on the supports including cobalt phthalocyanine and copper phthalocyanine, and the types of immobilized noble metals. The experimental results show that w=1% RGO doping with w=3% Pd-Pt (n_Pd∶n_Pt = 1∶1) alloy catalyst has the highest selectivity on the reaction, and the yield of benzyl alcohol is up to 81%. The results also demonstrate that Pd is the active sites of the Pd-Pt/RGO-g-C₃N₄ catalyst for the selective hydrogenation of benzaldehyde. The loading of Pt enhanced selectivity of the bimetallic Pd-Pt/RGO-g-C₃N₄. The study performed in this work shows that the supported Pd-Pt/RGO-g-C₃N₄ catalyst addresses the traditional problems of low photocatalytic efficiency, and successfully realizes the highly selective conversion of aldehyde into alcohol molecules.