To　reduce　the　effects　of　surface　characteristics　of　materials　and　background　noise　of　a　magnetic　excitation　field,　a　new　sensor　with　magnetic　shielding　was　developed　for　eddy-current　(EC)　testing.　Based　on　the　analysis　of　EC　theory,　the　performances　of　different　cores,　including　air　core,　solid　cylindrical　ferrite　core,　hollow　cylindrical　ferrite　core,　and　magnetic　shielding　ferrite　core,　were　analyzed.　The　simulation　results　show　that　the　magnetic　shielding　core　can　increase　the　EC　density　in　the　test　material.　External　magnetic　field　shielding　can　effectively　improve　the　defects＇　detection　sensitivity　and　the　detection　depth　of　subsurface　defects.　According　to　the　simulation　results　of　finite-element　excitation,　a　bidirectional-excitation　EC　sensor　with　magnetic　shielding　was　prepared　and　optimized　according　to　the　orthogonal　experiment.　Finally,　the　experimental　results　show　that　it　can　effectively　detect　the　notch　defects　of　a　10-mm-thick　stainless　steel　plate　surface　at　a　distance　of　7　mm.　A　linear　relationship　was　observed　between　the　change　of　impedance　amplitude,　phase　difference,　and　depth　of　subsurface　defects.