Since the 1970s, the use of sunlight to split water to convert solar energy into clean and renewable hydrogen fuel has become the focus of attention. Solar energy is an inexhaustible energy, and seawater is the most abundant and readily available natural resource on the earth. The use of photoelectrocatalytic seawater splitting to produce hydrogen has become one of the ideal ways to solve the actual energy problem and alleviate the shortage of fresh water resources. This review summarizes the research work that has been explored so far for hydrogen evolution by photoelectrocatalytic seawater splitting, combs the research content and mechanisms, and prospects the field of photoelectrocatalytic seawater splitting.