The utility model discloses a device capable of automatically eliminating cathode fouling, comprising a PLC controller, relays, ruthenium-indium-titanium electrodes, a current sensor, a main loop, a secondary loop, and the like. A relay of a cathode of the main loop is switched off and relays of the secondary loop are switched on when the PLC controller detects that the current of the main loop is decreased, and the cathode is served as an anode in the secondary loop, thereby realizing the positive and negative conversion of the electrode, and eliminating the surface fouling. After a few minutes, the relays of the secondary loop are switched off, and the relay of the main loop is switched on, the electrode is continued to use as the cathode in the main loop. The surface fouling of another cathode is eliminated by using the same method. After eliminating the cathode fouling, the cathodes are all accessed to the main loop for providing power for a main junction box. By repeating the cycle, the surfaces of the cathodes can be kept clean. By adopting the device capable of automatically eliminating cathode fouling, the fouling on the surfaces of the cathodes can be eliminated on the basis of non-interrupting power supply, the power supplying efficiency is improved, and the service life of the cathodes can be prolonged.