Nanostructured semiconductor composites are often considered as types of promising photocatalysts and display great prospects in visible light photocatalytic hydrogen production. In this work, nanostructured Pt-on-Au/PCN composites were synthesized by photo-induced synthesis strategy with exfoliated g-C3N4(PCN) nanosheets as starting materials and served in visible light photocatalytic hydrogen production. The prepared Pt-on-Au/PCN composites showed enhanced visible light absorption and photocatalytic hydrogen production performance. The visible light photocatalytic performance of Pt-on-Au/PCN composites is approximately 54.60 times of pristine g-C(3)N(4)and 3.61 times of Pt/g-C(3)N(4)composites, respectively. These findings could be mainly attributed to the formation of bimetal Pt-on-Au nanostructure for visible light harvesting and charge separation. Besides, possible photocatalytic mechanism of nanostructured Pt-on-Au/PCN composites for hydrogen production is proposed in detail. Current work also offers a new method to design and synthesize other types of metal-on-metal nanostructures for efficient semiconductor photocatalysis.