Abstract: In order to put forward the parameter configuration of C₄F₇N/CO₂ gas mixture meeting the requirements of liquefaction temperature and insulation at low temperatures, the liquefaction characteristics and low-temperature insulation characteristics of C₄F₇N/CO₂ gas mixture were studied. The liquefaction temperature of C₄F₇N/CO₂ at different gas pressures and mixing ratios was obtained through experiments and calculation. The calculated liquefaction temperature was in good agreement with the test data. The breakdown voltage of C₄F₇N/CO₂ gas mixture was obtained by carrying out AC breakdown tests at different temperatures. It is found that the standard deviation of the breakdown voltage of the gas in the liquefaction stage is 2~7 times that of the liquefied gas, and the insulation performance of the liquefied gas mixture decreases significantly with temperature. At this time, the breakdown voltage is only related to temperature and no longer affected by the mixing ratio. The temperature of –25 ℃ and –30 ℃ is taken as the minimum service temperature, and the C₄F₇N/CO₂ mixture parameter configuration scheme meeting the requirements is proposed, which can provide reference for the application of C₄F₇N/CO₂ mixture at low temperatures.