Abstract: Mediator complex subunit (MED) is a highly conserved multiprotein complex which is widely existing in yeast and mammals, and it is involved in the information transfer process between transcription factors and RNA pol-II. As one of the subunits of human mediator complex, MED19 is closely related to human growth and development, especially to tumorigenesis and development. In this paper, the research advances in the structure and biological function of human MED19 will be reviewed to provide ideas for subsequent research on MED19.