Abstract: The present invention discloses a cellular structure of a silicon carbide UMOSFET device having surge voltage self-suppression and self-overvoltage protection capabilities. A p-well region of the cellular structure is divided into three layers; the top layer is on the left and right sides of a U-shaped trench and in contact with the U-shaped trench; the middle layer and the bottom layer are respectively constituted by two parts on the left and right sides of the cellular structure, and the left and right parts of the two are not in contact; the distances between the left and right parts of the middle layer and the vertical axis of the cellular structure are greater than the distances between the left and right parts of the bottom layer and the vertical axis of the cellular structure; that is, a JFET structure is introduced to a drain current path of the cellular structure.