Pressure relief valve

The invention discloses a pressure relief valve comprising a tubular housing, a gas incoming port located at one end of the housing, a seal which is located at the other end of the housing and which is installed with the housing in a sealed manner and a plurality of pressure relief exhausting ports located in the side wall of the housing. The pressure relief exhausting ports are arranged symmetric about the central axis of the housing; a seal ring is tightened through the mutual stress between a roller wheel and a seal baffle, large tightening force can be applied to the seal ring, and the fine tightness effect is achieved; in the repeated opening and closing processes, the pressure relief valve is high in structural stability and is prevented from failures. A piston is in a cylindrical structure, the front and rear ends are provided with a sliding plate and a sliding ring for supporting and sliding, and the structure is symmetrical and stable accordingly.