The　equivalent　resistance　of　eddy　current　power　losses　was　proposed　in　the　paper　as　characteristic　parameter　of　metal　target　information,　which　was　in　direct　proportion　with　sixth　power　of　detection　distance.　Using　the　method　of　pulse　width　modulation　for　detection　coil　and　by　detecting　the　change　of　coil＇s　freewheeling　process,　the　equivalent　resistance　of　eddy　current　losses　could　be　measured.　It　could　not　only　determine　the　distance　but　also　eliminate　environmental　interference　and　improve　anti-jamming　capability　by　measuring　area　difference　of　coil＇s　freewheeling　process　between　whether　there　is　a　target.　Target　signal　detection　circuit　was　designed　and　target　properties　measurement　results　were　given.　©　Springer　International　Publishing　Switzerland　2014.