SF₆ is widely used in electrical insulation equipment due to its excellent electrical properties, but its greenhouse effect is extremely detrimental to the atmospheric environment. In recent years, C₅F₁₀O, as an environmentally friendly SF₆ potential substitute gas, has attracted the attention of researchers around the world. In order to further explore the insulation properties of C₅F₁₀O/Air and C₅F₁₀O/N₂, a gas insulation performance test platform are used to conduct power-frequency breakdown tests under two quasi-uniform electric fields for two gas mixtures under different pressures and different C₅F₁₀O partial pressures. The experimental results show that the insulation strength of C₅F₁₀O mixed gas increases with the increase of gas pressure. Increasing the partial pressure of C₅F₁₀O can also increase the insulation strength of the two types of buffer gases, and the relative increase in insulation strength of N₂ is greater than that of dry air. From the viewpoint of dielectric strength, C₅F₁₀O /Air has more potential to replace SF₆ in indoor low-voltage equipment than C₅F₁₀O /N₂ mixed gas by appropriately increasing the C₅F₁₀O mixed gas pressure and C₅F₁₀O partial pressure.