The invention discloses an electrical impedance tomography-based metal plate flaw detection system, and belongs to the technical field of testing. The system comprises a plurality of electrodes uniformly arranged around a detected metal plate, a measurement device and a processor, wherein the electrodes are connected with the measurement device through wires; the measurement device is connected with the processor through a data line. According to the system, the electrodes are arranged around the detected metal plate, measured voltage data is transmitted to the processor through the measurement device, then an electrical conductivity distribution image in the metal plate is reconstructed by adopting a corresponding image reconstruction algorithm, and whether the quality problems of impurities, cracks and the like exist in the metal plate or not can be judged according to the image, so that an internal structure flow of the metal plate can be detected.