Abstract: Multi-Layer metal materials are widely used in aerospace, defense industry, nuclear industry and other important fields. There are defects in the interior part of the structures. Because of the particularity and complexity of this material, it is a challenge task for traditional nondestructive testing methods to detect these defects. This paper proposes a magnetic concentrated pulse eddy current detection technology to improve the detection capability of the internal defects. The detection sensitivity of the internal defects is improved through the optimization of the structural parameters of the eddy current probe and the design of the magnetic shielding shell. Finally, experimental tests of defects with different sizes in the multi-layer structures are conducted to verify this study.