Abstract: To study the discharge decomposition characteristics of eco-friendly C₄F₇N/CO₂/O₂ ternary gas mixture, the decomposition experiments of C₄F₇N/CO₂/O₂ ternary gas mixture under corona discharge were carried out with different O₂ volume fractions. The main decomposition products include CF₄, C₂F₆, C₃F₆, C₃F₈, C₆F₁₄, CNCN and CF₃CN, in which the production of saturated fluorocarbon gases such as CF₄, C₂F₆ and C₃F₈ is high, while the production of unsaturated fluorocarbon gases C₃F₆ is low. The addition of O₂ can significantly inhibit the gas decomposition, after 60 h corona discharge of the gas mixture with 4% O₂ volume fraction, the production of CNCN is only 22.1% of that in the absence of O₂. With the increase of O₂ volume fraction, the formation rate of CNCN and other decomposition products decreases rapidly at first and then tends to be stable, and 2% to 8% volume fraction of O₂ has good inhibitory effect on the decomposition of the gas mixture. Based on the density functional theory, the simulation analysis of the decomposition process was carried out. It is found that O₂ will consume a large amount of free radicals by reacting with CF₃, CN, CF₃CFCN and other radicals, resulting in the inhibition of the formation of the main decomposition products with these free radicals as reactants.Under the action of O₂, the formation rate of main decomposition products shows a nonlinear variation with the increase of O₂ volume fraction. The ratio of C₂F₆/CF₄ is relatively stable, and it has a potential to be used as an indicator for corona discharge identification of C₄F₇N/CO₂/O₂ ternary gas mixture.