The invention discloses a protective resistor for use in an ultrahigh-voltage very fast transient overvoltage test, which comprises a connecting flange, a resistor body, middle uniform rings and end uniform rings, wherein the resistor body comprises an insulating barrel which is wounded with at least two layers of resistance wires; both of the two ends of the insulating barrel are connected with a connecting flange by a middle uniform ring; the other end of each connecting flange is connected with an end uniform ring; spiral grooves are formed on the outside surface of the insulating barrel; the resistance wires are wound in the spiral grooves; and the outside surface of the insulating barrel is wounded with an epoxy glass silk ribbon and cured after being wounded with each layer of resistance wires. When the embodiment of the invention is used, the structural deformation or insulation damage of the protective resistor used outdoor are prevented.