The invention discloses an anti-reversing device of an isolation switch. A steering sensor is used for sensing the direction of the main shaft of the isolation switch, and according to the sensing signal, whether the rotation direction of the main shaft is consistent with the preset rotation direction is judged. If the actual rotation direction of the main shaft is opposite to the preset rotation direction, change of a motor power supply of the isolation switch is controlled, so the rotation direction of the motor is changed, and the actual rotation direction of the motor is allowed to be consistent with the preset rotation direction. Thus, the rotation direction of a cross rod of the isolation switch is allowed to be consistent with the operation of actual switching on or switching off of workers. The motor power supply are prevented from being connected wrongly to cause that the rotation direction of the cross rod of the isolation switch is inconsistent with the preset direction and cause a burning down phenomenon of the motor power supply. There is no need for workers to manually detect whether the wiring between the motor and the power supply is correct, so working intensity of the workers is reduced and working efficiency is improved.