The quantitative analysis and formation mechanism of the decomposition products of (CF₃)₂CFCN/CO₂ mixture under breakdown discharge have some defects. Therefore, the decomposition products of (CF₃)₂CFCN/CO₂ gas mixture after multiple AC breakdown discharge are quantitatively detected by gas chromatography-mass spectrometry, and the difference of product contents are analyzed in this paper. In addition, based on density functional theory, the decomposition and product formation path of (CF₃)₂CFCN/CO₂ mixed gas and the stability of (CF₃)₂CFCN are analyzed from microscopic view. The enthalpy change and reaction rate of each reaction at different temperatures are calculated. The research shown that the decomposition products of (CF₃)₂CFCN/CO₂ mixed gas are mainly CO, CF4, C₂F6, C₃F8, CF₃CF₂CF₂CF₃, C₂F4, C₃F6, CF₃C≡CCF₃, CF₂=CFCF₂CF₃, CF₃CN, C₂F5CN, C₂N₂ and HF, and the decomposition products are mainly small molecular compounds. The volume fractions of saturated and unsaturated fluorocarbons trend to decrease with the increasing carbon atoms number, and the total volume fractions of saturated fluorocarbons are relatively larger. The increasing temperature accelerate the decomposition of (CF₃)₂CFCN to generate CF₃ radicals. The relevant results reveal the decomposition characteristics of (CF₃)₂CFCN/CO₂ mixed gas under AC breakdown discharge, which provides a reference for the application and maintenance of mixed gas.