In order to comprehensively reveal the fire-extinguishing reaction path of perfluorobutyl methyl ether,its fire extinguishing performance and fire extinguishing mechanism were investigated by combining experimental and theoretical methods.The fire extinguishing performance of perfluorobutyl methyl ether was evaluated by cup combustion test,and its high-temperature thermal decomposition process was simulated by a gas high-temperature pyrolysis mechanism analysis platform,and the pyrolysis products at different temperatures were analyzed by gas chromatography-mass spectrometry.It was found that the critical fire extinguishing volume fraction of perfluorobutyl methyl ether was about 5.90%,and the fire extinguishing performance was good.The initial thermal decomposition temperature of perfluorobutyl methyl ether was 400 ℃,and the pyrolysis products include nonafluoro-1-butane,octafluoro-1-butene,hexafluoropropane and trifluoromethane.The test results revealed the fire-extinguishing mechanism of perfluorobutyl methyl ether,indicating its potential to become a substitute for halon fire-extinguishing agents.