SF6 decomposition products can be used to detect partial discharge (PD), but the metal materials in a PD area can significantly affect SF6 decomposition characteristics. Disregarding the effect of metal materials on such characteristics inevitably result in certain errors when using them to diagnose the internal insulation faults of gas-insulated switchgears. This paper investigates the influence regularity on the main stable decomposition components of SF6 (namely SO₂F₂ and SOF₂) of the commonly metal materials uesd in GIS, such as aluminum (Al), copper (Cu) and stainless steel (SS). Firstly, an experimental platform is constructed to simulate SF6 decomposition under a PD area, and the influence regularities of Al, Cu and SS on the concentration, formation rate and saturation time of SO₂F₂ and SOF₂ are obtained. Secondly, the influence mechanism of Al, Cu and SS are preliminary explored combined with the chemical activity of the metal materials.