Aiming at electromagnetic excitation acoustic emission for barrel crack detecting,the principle and implementation of electromagnetic acoustic emission was analyzed in detail.The excitation experiment of acoustic emission of metal pipe crack was carried on by a largecapacity and highvoltage capacitor discharge method.Acoustic emission signals was collected on cracks and no crack specimens under different excitation voltages;then the signals were comparative analyzed in frequency domain.The law of electromagnetic excitation acoustic emission of metal pipe crack was obtained which provided a basis for the barrel crack detection by acoustic emission under normal.