Abstract: Mitogen-activated protein kinases(MAPKs) are the serine/threonine protein kinases in eukaryotes, they are phosphorylated by MAPKK and become activated, and then transfer signals by phosphorylating the serine or threonine residue of the substrate protein. MAPKs are components of the MAPK cascades which involved in the transduction of extracellular signals to intracellular targets and regulation of special genes’ expression. Distinct MAPK cascades are regulated by different extracellular stimuli and are implicated in a wide variety of biological processes. In this paper , the curren advances in studies on MAPKs and MAPK cascades are reviewed, including the structure characteristic, action machanism, biological function of MAPK and the regulation of MAPK cascades.