The new environmentally friendly insulating gas C4F7N is an important medium for insulating applications replacing the strong greenhouse gas SF6, and its decomposition characteristics on the electrode surface and its interaction characteristics with impurity particles are important factors affecting its long-term insulating performance. In this paper, density functional theory (DFT) calculations are carried out based on the first nature principle to investigate the influence of the dissociative particles H, O and OH of microaqueous and microoxygenic impurities on the Cu(111) surface of the copper electrode on the dissociation reaction of the C4F7N molecule, as well as the impurity radical interaction and the generation of the typical characteristic decomposition component COF2. The simulation results show that the impurity particles inhibit the dissociation process of C4F7N molecules to a certain extent, the defluorination is the most easily occurring dissociation reaction, and the neighboring preadsorption of different impurity molecules affects the bonding characteristics of the dislodged particles on the Cu(111) surface after the dissociation of C4F7N molecules. This study provides a theoretical reference for the correlation of the dissociation properties of C4F7N molecules on the electrode surface in the presence of impurity particles.