Combining semiconductor nanocrystals with metal particles has proven as a useful approach of improving the photocatalytic activity. On the other hand, yolk@shell nanocrystals with interior, void space can provide large surface area and homogeneous environment for reactant molecules, both of which are favorable for catalytic applications. In this work, Au@Cd1-xZnxSe yolk@shell nanocrystals with tunable compositions (x values) were prepared and used for photocatalytic hydrogen generation. The enhanced photocatalytic activity of Au@Cd1-xZnxSe was attributed to the pronounced charge separation induced by the Au yolk as well as the abundant active sites endowed by the yolk@shell structures. The interfacial charge dynamics were examined with time-resolved photoluminescence spectroscopy, which revealed the effectiveness of the optimal composition in achieving the most significant charge separation in concert with the highest photocatalytic activity.