Abstract: Relevant research on non-destructive testing technology for metal plate defects is very comprehensive, and it can achieve the detection, quantification and 3D imaging of defects. However, the defect detection sensitivity of traditional non-destructive testing method is limited by many conditions and the complexity of the algorithm, making it difficult to detect small defects. Therefore, as the first attempt of the negative corona discharge method in the field of non- destructive testing, this paper innovatively proposes a metal plate defect detection method based on the Trichel pulse in negative corona discharge. The charged particles are sensitive to the electrode structure, which are used to make a preliminary judgment on the existence and severity of defects by analyzing the Trichel pulse current as the external characteristic of the negative corona discharge phenomenon. Moreover, the corona detection geometric and simulation models are established, and a needle-to-plane discharge experiment platform is built to verify the simulation results. Results show that by analyzing the unique Trichel pulse waveform parameters, we can effectively identify whether the metal plate has defects or not. We believe that this method has certain application potential in the high-sensitivity defect detection.