A nanohybrid of CdS and HCa2Nb3O10 with enhanced separation of charge carriers was conveniently prepared by self-assembly of negatively charged HCa2Nb3O10 nanosheets with the existence of Cd2+ followed by sulfuration. With CdS working as a visible light absorbent, HCa2Nb3O10, with a wide bandgap, showed H-2 evolution activity without cocatalysts upon visible light excitation and neutral pH (450 mu mol h(-1) g(cat)(-1)), and showed a high quantum efficiency of 7.2% at 425 nm because of enhanced charge separation. The self-assembly method rapidly realized introduction of guest materials into the interlayer space of layered perovskites from a layer-bylayer strategy, showing great potential in synthesizing novel 2D material based hybrid photocatalyst. A type II composite band structure was obtained from combination of CdS and niobates, making it possible for spontaneous charge separation. While ultra-fine nature of the guest CdS, ultra-thin nature of the host niobate nanosheets and close junction between the host and guest components facilitated charge transfer between components. Enhanced charge separation in hybrid photocatalyst is the key factor that leads to its superior photocatalytic performance in comparison with its components. This work extends photocatalytic application of wide gap niobates into visible light region. Since the unique nanostrucute and charged nature of 2D materials can be fully utilized, it is believable that more efficient photocatalytic water splitting can be realized by constructing nanosheets based hybrids in the future.