Abstract: through the study of 66 kV dry hollow reactor short circuit fault, according to the field inspection and structure point, to inspect the equipment disintegration, found that the surface of the obvious wool and bird excrement, and the 7th and 8th coating have excessive smoke, and gradually deteriorate, the interlayer and strands insulation damage, finally makes the reactor failure. Therefore, the corresponding preventive measures are put forward to ensure the safe operation of the equipment.