Objective Fucoidan i购买Panobinostats a water-soluble polysaccharide composed of L-fucose and organic sulfate groups, mainly exists in the cell wall matrix of brown algae. It has significant immunomodulatory activity and has good development value in food and medicine fields. Here we systematically summarize the immune regulatory mechanism of fucoidan, and the relationship between the chemical structure and immune regulation in this paper, aiming to provide reference basis for deeper study and development of the structure-activity relationship of fucoidan. Methods: We used the Fucoidan, Chemical modification, Immune regulation, and Biological activity as search terms, conducted literature searches on databases such as PubMed, Web of Science, MEDLINE, China Knowledge Network, Wanfang Database, and Vip Database.The literatures of the past decade were selected and analyzed. Results: Fucoidan can significantly increase the immune organ index of the spleen and thymus, and enhance the activity of immune organs and promote the proliferation of immune cells and improve the cellular and molecular immune response levels, regulate the cytokine secretion. Moreover, fucoidan stimulates the innate and adaptive immune defense systems of the body by interfering with the process of virus adsorption, transcription, and synthesis, which can be used as an immune adjuvant to increase the production of antigen specific antibodies in the body. It can bind to receptors, then activates the intracellular pathways, activates immune cells, promote the release of cytokine and enhance immune activWnt-C59研究购买ity. The relative molecular weight, monosaccharide composition, glycosidic bond types, chemical modifications,confirmed cases and advanced conformation of fucoidan can affect its immunomodulatory activity. Conclusion: This paper has significance for further studying on the range of molecular weight, monosaccharide types, glycosidic bond types, chemical modification methods and advanced conformations of fucoidan, and it is of great significance in revealing its structure-activity relationship and developing more effective analogues or derivatives as novel drugs for disease treatment.