The invention relates to a pressure relief device. The pressure relief device is a rectangular basin, wherein the rectangular basin is provided with flanging edges arranged in the same plane, the basin bottom has two layers, a plurality of long rectangular through holes are formed in an inner side of a through hole, for fastening, of a long flanging edge, are arranged in a straight line and are parallel to the long flanging edge, the pressure relief device is connected onto an outlet of a pressure relief passage on a switch cabinet, the through hole, for fastening, formed with the long rectangular through holes is matched with a metal bolt, the through hole, for fastening, in the other long flanging edge is matched with a nylon bolt, and through holes are formed in a mesh plate and conform to IP4X protection grade requirement. By the pressure relief device, heat can be timely and effectively dissipated; meanwhile, the positions where the long rectangular through holes are located are bent under the impact of fault pressure, the pressure relief device is opened to one side connected with the metal bolt, the fault pressure is finally relieved, thus, the pressure relief device cannot be rushed to fly, and the requirements of temperature reduction and fault pressure relief of the switch cabinet can be met; and the pressure relief device is simple in structure and high in practicability.