The invention relates to a decontamination system and a decontamination method. The decontamination system comprises a reaction device and a power supply device, wherein the reaction device comprisesa cathode and a liquid absorption assembly; the liquid absorption assembly comprises a liquid absorption part used for absorbing an electrolyte; the liquid absorption part can be in contact with the cathode and a to-be-decontaminated workpiece, so that the liquid absorption part can provide the electrolyte for the cathode and the to-be-decontaminated workpiece; the power supply device is providedwith a positive electrode and a negative electrode; the positive electrode can be electrically connected with the to-be-decontaminated workpiece; and the negative electrode can be electrically connected with the cathode. According to the decontamination system, site decontamination can be achieved on the to-be-decontaminated workpiece, and less secondary effluent is generated.