The composites of CdS@g-C3N4/Ni(OH)(2) was prepared by photo-deposition method. The co-catalyst Ni2+/Ni clusters reduced from Ni(OH)(2) can provide active sites on the surface of CdS@g-C3N4, which significantly accelerate the separation of electron-hole pairs though the special channel formed between CdS and g-C3N4. This way further improved the H-2 production activity for 1445.5 mu mol, which was 39.5 times and 149.0 times then pure CdS and g-C3N4, respectively. The AQE corresponding to the produced H-2 was 5.59%. The morphology, crystal structure and chemical valence of the elements were characterized by SEM, HRTEM, XRD, XPS, UV-Vis, etc. The photoelectrochemical properties of CdS@g-C3N4/Ni(OH)(2) was measured by steady-state fluorescence and electrochemical. The results show that composite catalyst posses a high photoelectric density and well light absorption properties. the purpose of high H-2 production and fleet charges separation is achieved. Simultaneously, the reaction of H-2 production mechanism was proposed under the condition of lactic acid solution as a sacrificial reagent. [GRAPHICS] .