Abstract: In recent years, C₅F₁₀O has attracted wide attention because its excellent insulating properties and environmental protection properties. C₅F₁₀O gas mixture has begun to apply in equipment such as gas insulation ring network cabinets. The research on the detection method of the decomposition components of the C₅F₁₀O mixed gas is of great significance for the fault diagnosis and operation and maintenance of equipment. Consequently, taking the thermal decomposition products of C₅F₁₀O/N₂ mixed gas as the research object, we built a Fourier transform infrared spectroscopy(FTIR) platform. By using the FTIR technology, we explored the types of C₅F₁₀O/N₂ mixed gas pyrolysis components, and compared them with gas chromatography mass spectrometry(GCMS) detection results to determine the feasibility of FTIR to detect the decomposition components of mixed gas. Through FTIR detection and analysis, it is determined that the decomposition group after pyrolysis of C₅F₁₀O/N₂ contain CF₃H, C₃F₆, C₃F₇H, CO, CO₂ and CH₄ gases. The absorption spectra of CF₃H, C₃F₆, and C₃F₇H are analyzed, and the concentration calibration model is established. It is confirmed that the detection method of FTIR technology can be adopted to quantitatively analyze CF₃H, C₃F₆ and C₃F₇H gases in the bands of 1130~1170, 1020~1050 and 890~930 cm^–1, respectively. The obtained concentrations of CF₃H, C₃F₆ and C₃F₇H are 21.34×10^–6, 27.39 ×10^–6, and 7.78×10^–6, respectively, which are similar to the detection results of GCMS at 20.88×10^–6, 27.88×10^–6, and 7.62×10^–6. The research in this paper can provide a reference for the detection of decomposed gas in the overheating fault of C₅F₁₀O/N₂ mixed gas insulation equipment.