Interleukin 6 (IL-6) is a multifunctional cytokine，whose biological effects mainly depend on the structure and function of IL-6 receptor. IL-6R is composed of two polypeptide chains，a ligand-binding receptor gp80(IL-6Rα)，and a nonbinding signal transducer gp130 (IL-6Rβ).The two subunits share the function and cooperate with each other，and form high affinity IL-6R after gp80 chain binding IL-6. The haemopoietic domain in IL-6Rα chain is capable for binding IL-6. However，gp130 is shared by several cytokines as their common signal transducer. Cytoplasmic portion of gp130 has some conserved amino acids which are related to actieating some tyrosine kinases .The homodimerization of gp130 induced by IL-6+IL-6R complex can activate a series of kinases and transcription factor and finally leads to related genes expression.