A capacitor insulation system is disclosed in the present application. The insulation system includes a dielectric fluid containing a first voltage stabilizing additive of a first concentration. The insulation system further includes a dielectric film containing the first voltage stabilizing additive of a second concentration and impregnated in the dielectric fluid. The first concentration is greater than the second concentration. The insulation system prepared according to the present disclosure can provide an increased and quite stable dielectric strength.