Cable joint lead sealing part pulsed eddy current detection method and system

The invention discloses a cable joint lead sealing part pulsed eddy current detection method, which comprises the following steps that a direct current square wave excitation signal is inputted into an excitation coil close to a cable joint lead sealing part, the generated primary transient magnetic field passes through an insulating layer outside the cable joint lead sealing part, is conducted to a detected metal surface inside the cable joint lead sealing part and generates eddy current on the metal surface; when the phase of the direct current square wave excitation signal is changed from positive to negative, a fast changing reverse current is generated, the reverse current generates an eddy current with the direction opposite to that of the eddy current generated by the primary transient magnetic field, and an attenuated secondary magnetic field is induced on the surface of the detected metal in the cable joint lead sealing part,and an induced voltage signal of the secondary magnetic field is detected th