Abstract: The plasmon resonance effect of the metal nanoparticles is of great benefit to improve the efficiency of solar water splitting. However, the metal Cu is easy to be oxidized, and a complex transfer process of hot electrons exits in Cu/TiO₂ interfaces. In this work, the hierarchical Cu/TiO₂ nanobowl arrays were prepared and a SiO₂ interlayer with a thickness of 10-15 nm was introduced between the interface of Cu and TiO₂. The solar water splitting performances and the mechanism of plasmonic Cu metal were investigated by combing the experiment with simulation. Results show that the Cu₂O film formed by the oxidation of Cu in Cu/TiO₂ can assist the injection of hot electrons, but has an inhibitory effect on the light absorption of Cu. It has a positive effect on enhancing light absorption and blocking hot electron migration after adding the SiO₂ interlayer. The plasmon energy transfer promotes the formation of more photogenerated electron-hole pairs. Therefore, the Cu/SiO₂/TiO₂ nanobowl arrays exhibit the enhanced photoelectrochemical performance.