Abstract: Polytetrafluoroethylene (PTFE) has good heat resistance and mechanical properties and has gradually become the mainstream insulation material for aviation cables. To satisfy the requirements of increased voltage level for the power supply system of more electric aircraft and the insulation in the complex environment and aviation conditions, it is urgent to further improve the electrical resistance of cable insulation. In this paper, five kinds of PTFE samples were prepared by magnetron sputtering TiO₂. The water contact angle and conductivity of the modified samples were tested. The electrical resistance of the sample surfaces was analyzed by flash and electrical aging experiments, and the mechanism of the effect of magnetron sputtering was explained based on the surface trap distribution. The results show that the surface hydrophobicity of the modified samples is improved and the conductivity is reduced. With the growth of magnetron sputtering time, the flashover voltage and anti-electro-aging properties of PTFE surface are first enhanced and then decreased, and the effect is best at 45 min of modification. The surface charge trapping capability is enhanced after splashing inhibits the development of discharge, resulting in an increase in flashover voltage. Deep traps capture charges, forming a reverse electric field that suppresses the injection-extraction process of free charges and improves the electrical aging resistance of PTFE.