The design of back-fire relief valve is based on the principle that silk screens or small holes on corrugated boards have extinguishing effects on subsonic or ultrasonic flames in pipes. It can be widely used in gas purification and ventilation systems, gas assay systems, coal mine mashgas emission systems, and pipe networks of heating furnace fuel gas, natural gas, and petroleum liquefied gas, to effectively ensure the normal operation of gas pipes and gas usage sites.