Efficiency and stability are the two key points for CdS photocatalyst because its application has been seriously restricted owing to serious photocorrosion issue and the recombination of photo-induced charge pairs. In this paper, CdS nanoparticles (NPs) were surface-modified by chemical inert Al₂O₃ shell. This modification could prevent nascent formed oxygen induced photo-corrosion and enhance the photo-stability of CdS during water splitting significantly. In addition, it was found that such a shell could enhance efficient separation of photo-induced charge pairs. Besides, with the assistance of artificial gill of removing nascent formed O₂ from water, Pt/CdS@Al₂O₃ photocatalyst can achieve overall water splitting under visible light irradiation. The rate of H₂ evolution increased 126 times over Pt/CdS@Al₂O₃ composite compared with pure CdS NPs, and the stability was maintained in several cycles of reaction without any decrease. The measurement of concentration of Cd²⁺ in solution after long cycles by ICP method confirmed this anti-photo-corrosion property of Al₂O₃ shell on CdS. This work provides a new potential way to design and fabricate more stable and efficient CdS-based nanocomposite photocatalysts for versatile solar energy conversion.