Lycium barbarum polysaccharides (LBP) are one of the major functional components in the fruit of Lycium barbarum, which have been demonstrated to exert immunomodulatory activity. Most of the existing studies are focused on the immunoenhancing effect of LBP, but in-depth research on its immunosuppressive effect is limited. This article reviews recent research on the immunoenhancing and immunosuppressive effects of different polysaccharide fractions extracted from Lycium barbarum fruit from different perspectives, like intestinal mucosa protection, intestinal flora changes, immune cells and the neuroendocrine immune system. The outcome of this review will be for the application of Lycium barbarum polysaccharides in antiviral therapy, antitumor therapy, vaccine development, immune-enhancing feed formulation and antiallergic agents or food products.