Plasmonic metal-semiconductor hybrid nanostructures have shown superior photocatalytic performance compared to conventional semiconductor. The enhanced solar energy conversion efficiency of hybrid nanostructures is attributed to the transfer of plasmonic energy from metal nanocrystals to semiconductor. The mechanism of photocatalysis and the plasmonic energy transfer process are highly dependent on the morphology of each component and their coupling manner. In this thesis, we developed the synthetic strategies for plasmonic metal-semiconductor hybrid nanostructures with desired configurations by combining Au nanocrystals with well-defined shape and semiconductors such as $Cu_2O$, $MoS_2$ and CdS. These hybrid structures exhibited excellent photocatalytic activity. Furthermore, we verified the correlation between the morphology of hybrid nanostructures and the mechanism of photocatalysis.