Interleukin-6 is a polypeptide that consists of two glycoprotein chains, which has molecular weight of 130kd. As an important member of cytokine network, interleukin-6 (IL-6) plays a central role in acute inflammatory reaction, and it can mediate acute phase reaction of liver, and stimulate production of C-reactive protein (CRP) and fibrinogen. Many infectious diseases may lead to rise in serum IL-6 level, and IL-6 level is closely associated with patient outcomes. As a pleiotropic cytokine with extensive functions, IL-6 is secreted by T cell, B cell, mononuclear phagocyte, and endothelial cell, and it’s a key part of inflammatory mediator network. Upon occurrence of inflammatory reaction, IL-6’s produced first, which induces production of CRP and procalcitonin (PCT) upon its production. It will be produced rapidly in case of infection, internal and external injuries, surgical operation, stress reaction, brain death, tumorigenesis, and acute inflammatory reaction process of other circumstances. IL-6 is involved in occurrence and development of many diseases, its blood level is closely associated with inflammation, virus infection and autoimmune disease, and its changes happen earlier than CRP. According to research results, IL-6 level increases rapidly upon bacterial infection, PCT level increases after 2h, while CRP only increases rapidly after 6h. Abnormal secretion or gene expression of IL-6 can often lead to occurrence of a series of diseases, large amount of IL-6 can be secreted into blood circulation in a pathological state, and detection of IL-6 is of very great significance to disease diagnosis and prognostic judgment.