Abstract: Photoelectrochemical (PEC) water splitting to produce hydrogen is a green energy production strategy that is expected to replace fossil fuels. Conventional photoelectrodes could lead to poor performance of water splitting due to their fast recombination and slow kinetics of photogenerated carriers. Injecting oxygen vacancies into the electrode materials can regulate the electronic and optical properties of the photoelectrodes, thus contributing to the formation of inherent defects in the photoelectrodes. It has been shown that introducing oxygen vacancies into photoelectrodes is an effective method to enhance the water splitting performance of PEC. For different types of semiconductor photoelectrode materials, the methods of introducing oxygen vacancies through hydrogen reduction, plasma treatment and hydrogen peroxide treatment, and the research progress of the effect of oxygen vacancies on the performance of photoelectrodes PEC were introduced. The in-depth understanding and new discoveries of oxygen vacancies based on new characterization techniques were summarized, and the strategies and applications of oxygen vacancies regulation in photoelectrodes were prospeced.