NOVELTY - Remediating groundwater polluted with reducing substances comprises using an anode reaction unit, a cathode reaction unit and an electrochemical reaction system of the direct current power supply. The reducing pollutant in groundwater has a semi-electrode reaction of oxidative degradation in the anode reaction unit, and the oxygen from air has reducing semi-electrode reaction in the cathode reaction unit, and the reaction speed is accelerated by applied direct current power supply.    USE - Method for remediating groundwater polluted with reducing substances (claimed).    DETAILED DESCRIPTION - Remediating groundwater polluted with reducing substances comprises using an anode reaction unit, a cathode reaction unit and an electrochemical reaction system of the direct current power supply. The reducing pollutant in groundwater has a semi-electrode reaction of oxidative degradation in the anode reaction unit, and the oxygen from air has reducing semi-electrode reaction in the cathode reaction unit, and the reaction speed is accelerated by applied direct current power supply. The anode reaction unit is arranged on a section of the underground flow, and the unit is filled with conductive material as anode. The permeability of groundwater is higher than that in stratum layer, and microorganism with electric respiration action is adhered to the surface of the anode. The microorganism has ability of transferring electron of reducing pollutant in groundwater entering the anode reaction unit to the anode to oxidize and degrade the reducing pollutant. The cathode reaction unit is arranged under ground or on the ground and is filled with materials for enabling oxygen or dissolving oxygen to have electrochemical reducing reaction as cathode, and the cathode is not in contact with the anode directly. The positive electrode of the direct current voltage is connected to the anode material of the anode reaction unit using lead wires and the negative electrode of the direct current voltage is connected to the cathode material of the cathode reaction unit with lead wires to control the output voltage of the direct current power supply and enable the electrode potential of the anode to be lower than the electric potential for eroding anode or separating out oxygen.