Abstract: To address the environmental impact of SF₆ gas, this paper focuses on the insulation performance of SF₆/N₂ and SF₆/CO₂ gas mixtures. For SF₆/N₂ mixtures, under pressures of 0.11~0.15 MPa and electrode gaps of 5~25 mm, the AC breakdown characteristics in R_0.5-plane and R₆-plane electrode configurations are analyzed. Results show a linear rise in breakdown voltage with pressure and gap distance, with electrode configuration significantly affecting breakdown voltage. Additionally, after 40 breakdown tests on SF₆/CO₂ and SF₆/N₂ mixtures, it is found that the insulation strength of both decreases with increasing breakdown, yet SF₆/N₂ has better insulation performance. Furthermore, the R₆-plane configuration shows a higher breakdown voltage due to its more uniform electric field distribution, as indicated by the calculated field efficiency factor. This research offers a key reference for selecting SF₆ alternatives in high-voltage equipment.