Abstract: Ulva lactuca polyphenols are secondary metabolites of green algae and have been experimentally proven to exert diverse biological activities. The content and biological activity of polyphenol extracted from U. lactuca depends not only on the growth environment and climatic conditions, but also on the extraction method and operation steps. This review aims to provide an overview of the extraction method, composition, and antioxidant, antibacterial, cholesterol lowering, anti-inflammatory as well as in vitro anti-cancer activities of polyphenol from U. lactuca. The application prospect of U. lactuca polyphenols in food and medicine field is also covered.