Summary: Polysaccharides are the most abundant bioactive compounds in , and have been widely used as dietary supplements in traditional Chinese medicine for thousands of years. Polysaccharides from , exhibit unique biological properties, including anti-tumor, anti-inflammatory, and immunomodulatory activities. Herein, the sources and structures of polysaccharides from , were presented. This work also reviews the immunomodulatory activities and possible mechanisms of polysaccharides from , on different immune effector cells, including lymphocytes and myeloid cells. As an available adjunctive remedy, polysaccharides from , can potentially be applied for the modulation of the host immune system, namely the innate immunity, the cellular immunity, and the humoral immunity.