A magneto-optic/eddy current imaging system is used to test the defects at the surface or the subsurface of the metal samples in this paper. Excited by alternating current signals

alternating current magneto field is made from the excitation coil

transient eddy current is induced at the surface and subsurface of the metal sample

and the eddy current magnetic field can influence the induced magnetic field of the excitation coil. If there are some defects in the sample

they will vary the distribution of eddy current field

and then change the whole magnetic field. The polarization of the light will have a deflection angle when the light penetrates the optical rotation crystal film. Meantime

a magnetic-optic sensor placed parallelly to the sample surface can convert this change into optical intensity change. Finally the optical intensity change is received with CCD to realize visual nondestructive testing. The experimental results show that the system is feasible and appropriate.