Abstract: Photochemical reaction is one of the most important ways to reduce organic pollutants in surface seawater and control the environmental fate of these pollutants in seawater. Dissolved organic matter (DOM) is one of the most important factors affecting the photodegradation of organic pollutants in seawater. It can participate in the photochemical transformation of organic pollutants by absorbing sunlight to generate various photoreactive intermediates (such as ³DOM*, ·OH, and ¹O₂). With the development of extraction and characterization techniques for DOM derived from seawater, the study on the photochemical reactivity of DOM derived from seawater has been further promoted. This review provides a concise summary of the latest progress in the extraction, composition and structure characterization, photochemical reactivity of seawater DOM and the effect on photodegradation of organic pollutants. Finally, the research needs and challenges in the field of seawater DOM photochemistry are highlighted.