Abstract: In recent years, SF/N mixed gas instead of pure SF gas is used as the insulation medium for GIS busbars, 6 2 6 switches, transformers, bushings, and cable terminal chambers has gradually been promoted and applied in low-temperature areas. But pure SF gas is still used for GIS circuit breaker chambers. The temperature and pressure characteristics of the 6 mixed gas and pure SF gas were studied in the article, and the gas state equations and saturated vapor pressure values 6 corresponding to each pressure were derived and calculated. Temperature and pressure tests were conducted on SF/N mixed 6 2 gas and pure SF gas. Through theoretical calculations and comparative analysis of test results, the temperature and pressure 6 characteristic curves of the mixed gas GIS were drawn, providing a basis for the production of gas curve nameplates and low- temperature heating schemes for related GIS equipment.