Abstract:The immune system is a key system in the body responsible for executing immune responses and achieving immune functions. It can recognize and eliminate foreign substances with antigenicity and work together with other systems in the body to maintain the stability and physiological balance of the internal environment. Traditional probiotics，as active microbial preparations，play an important role in protecting the intestinal barrier，enhancing the body's immune system，and maintaining intestinal microbiota homeostasis. Inactivating probiotics or using only their fermented metabolites （i.e.，postbiotics） can endow hosts with similar immune regulatory effects through a mechanism similar to that of live probiotics. The composition of the immune system was reviewed，and the regulatory effects of active probiotics and their postbiotics on the body's immune function were summarized. It is expected to provide a theoretical basis for the potential use of non-toxic，longlasting，and stable postbiotics as a new and safe dietary supplement to address immune-related diseases in the future.