Abstract: Intestinal flora is an important part of the microecosystem, which participates in energy metabolism and immune regulation of the host, and has important physiological significance for the body. Numerous studies have shown that intestinal flora plays a vital role in the occurrence and development of diseases. Seaweed polysaccharides is a carbohydrate, which is extracted from seaweed and composed of multiple monosaccharides connected by glycoside bonds. Due to its anti-tumor, immunomodulatory, hypoglycemic and other biological activities, the research of seaweed polysaccharide has attracted extensive attention from scholars at home and abroad. Studies have found that seaweed polysaccharide can regulate the balance of intestinal microecological through promoting the proliferation of intestinal probiotics, inhibiting the growth of harmful bacteria, and thus play a therapeutic role in diseases. This paper summarizes the effects of seaweed polysaccharides on some diseases by regulating intestinal flora, aiming to provide reference for the development and utilization of seaweed polysaccharides, and provide new ideas for the prevention and treatment of related diseases.