The　rapid　growth　of　power　grid　capacity　and　the　widespread　use　of　a　large　number　of　power　electronics　and　non-linear　loads　have　led　to　harmonics　in　the　power　system.　Harmonics　in　the　power　system　will　cause　safety　hazards　to　the　normal　operation　of　power　equipment,　exacerbate　the　aging　of　insulation　materials,　and　reducing　the　overall　operation　reliability　of　the　system.　In　the　present　work,　we　used　power　frequency　ac　voltage　superimposed　harmonics　to　carry　out　ageing　experiments　on　power　cable　terminals.　Then,　we　tested　the　infrared　spectra,　dielectric　spectra,　electrical　conductivity,　and　surface　potential　decay　characteristics　of　silicone　rubber　insulation　materials　on　the　cable　terminals　aged　for　different　times.　The　experimental　results　show　that　the　dielectric　constant　and　dielectric　loss　of　silicone　rubber　gradually　increase　with　the　aging　time.　In　particular,　the　dielectric　loss　of　silicone　rubber　changed　greatly　at　low　frequencies.　The　effect　of　dc　conductance　of　aged　silicone　rubber　on　dielectric　loss　is　significantly　enhanced　at　low　frequencies,　which　causes　the　dielectric　loss　to　increase　as　the　frequency　decreases　following　an　inverse　power　law.　The　surface　potential　decay　rates　of　silicone　rubber　insulation　after　positive　and　negative　corona　charging　accelerate　with　increasing　the　aging　time,　which　is　consistent　with　the　experimental　results　of　electrical　conductivity.　By　analyzing　the　distribution　characteristics　of　electron　and　hole　traps　in　silicone　rubbers,　it　is　found　that　the　trap　energy　levels　of　electron　and　hole　traps　become　shallower　as　the　operating　time　increases.　The　calculation　of　the　carrier　hopping　conduction　model　shows　that　the　shallow　trap　formed　with　increasing　the　aging　time　will　lead　to　increases　in　both　carrier　mobility　and　conductivity.　When　the　conductivity　rises　to　a　certain　value,　the　silicone　rubber　will　lose　its　insulation　performance,　resulting　in　insulation　failure.