Abstract: Marine creatures have an abundance of polysaccharides, active proteins, active peptides, and amino acids. With advancements in separation extraction and structure-activity relationship analysis technology, marine animal polysaccharides, as important components of marine animal active ingredients, are shown to exhibit a variety of biological activities such as immune regulation, hypoglycemic activities, antioxidant effects, lipid-lowering processes, and anticancer properties. This article examines the different types, biological activities, and applications of polysaccharides in biomedicine, aquaculture, food, cosmetics, and proposes potential research directions for pursuit by providing theoretical reference to promote the high-value and ecological development and utilization of marine animals.