Firstly, the (001) plane oriented TiO2 nanosheet array film was prepared by hydrothermal method, and CdS nanoparticles were synthesized by hydrothermal method. The effects of hydrothermal reaction time on the structure and properties of the obtained films were investigated. Secondly, Cu element precursor was introduced into the hydrothermal reaction process in order to improve the photoelectrochemical performance of the composite film. And the effects of doping concentrations on the properties of the composite film were discussed. The results indicate that Cu element doping effectively broadens the light absorption range of the CdS sensitized TiO2 composite film (CdS/TiO2) and improves the photoelectrochemical properties of CdS/TiO2. When the hydrothermal reaction is carried out for 3 h and the Cu doping concentration was 1∶1 000, the photoelectrochemical properties of CdS/TiO2 are optimized.