C4F7N has emerged as one of the most promising next-generation eco-friendly insulating gases for replacing SF6 in power equipment. However, the gas–solid interfacial mechanisms, particularly the adsorption-induced decomposition behavior of C4F7N under discharge conditions, remain insufficiently understood. In this paper, the Ag(111) surface is selected as the representative electrode material to construct a molecular-scale gas–solid interface model. First-principles calculations reveal that C4F7N primarily undergoes physical adsorption on Ag(111), with no significant chemical bonding observed. As the external electric field increases, the adsorption energy is enhanced overall. Notably, downward electric fields synergize with surface negative charges to strengthen adsorption, whereas upward (forward) electric fields counteract the surface charge effect, resulting in reduced adsorption strength. Bader charge analysis shows that reverse fields promote electron injection into the molecule, while forward fields facilitate electron transfer to the metal surface. Due to its weak response to external electric fields and charge accumulation, Ag(111) demonstrates excellent interfacial compatibility and is thus a suitable anti-corrosion coating material for C4F7N -insulated equipment.