The invention discloses a rectangular sheet zinc oxide photocatalyst, a preparation method and application of the rectangular sheet zinc oxide photocatalyst to hydrogen production through photocatalytic water splitting, and belongs to the technical fields of inorganic metal oxide materials and energy storage and conversion. According to the method, a hydrothermal method is adopted, dissolvable zinc salt and a sustained release alkali source are taken as raw materials, and a rectangular sheet zinc oxide structure with highly consistent morphologies is synthesized under the influence of an anionic surfactant and hydroxyl ion. The formed rectangular sheet zinc oxide has high order and a large specific surface area, effectively promotes the diffusion and transportation of a carrier in photochemical reaction, can obviously improve the light energy capture efficiency when serving as a photocatalyst, and realizes efficient solar energy conversion. Experiment results show that the rectangularsheet zinc oxide structure has high photochemical activity, is still stable in performances after multiple light-catalyzed reaction processes, and has a good application prospect in the field of photocatalysis.