The utility model provides an installing support for a circuit fixed clearance overvoltage protector. The total length of the installing support is 200-350 mm, the width of the installing support is 25-65 mm, the thickness of the installing support is 3-8 mm, one end of the installing support is designed with an opening slot of which the diameter is 15-30 mm, the other end of the installing support is designed with an installing hole and a locating hole, wherein the diameter of the installing hole is 11-17 mm, the diameter of the locating hole is 3-7 mm, the middle part of the installing support is provided with a discharge electrode which is capable of being vertically adjusted for the alignment, and two clamping lugs are designed at the position, which is 4-7 mm far from an installing end of the opening slot. The installing support for the circuit fixed clearance overvoltage protector has the advantages that the electric performance and the mechanical performance are good, the heat deflection temperature is high, the moisture resistance and the fungus resistance are good, and the installing support is suitable for being used outdoors. Since the clamping lugs which play roles in slide preventing, dislocation preventing and strengthening and a locating bolt which is capable of preventing the installing support from rotating are designed at the installing position of the installing support, the installing support is simpler and more reliable; and since the installing support is provided with the discharge electrode, the circuit fixed clearance overvoltage protector is more convenient and reliable in work.