Magnetic　memory　test　technology　is　a　new　nondestructive　testing　technique,　which　is　able　to　detect　of　the　stress　concentration　area　and　potential　fault　of　low　speed　and　heavy　load　gear.　Because　the　magnetic　memory　signals　are　easy　to　be　disturbed　by　various　sources　of　noises,　a　new　method　based　on　the　intrinsic　time-scale　decomposition　(ITD)　is　proposed　to　achieve　the　extraction　of　magnetic　memory　signal.　Firstly,　the　magnetic　memory　signals　are　decomposed　into　several　proper　rotation　components　(PRC)　and　a　trend　component　by　ITD.　Then　reconstruct　the　first　four　order　PRCs　to　eliminate　the　low　frequency　cyclic　composition　of　magnetic　memory　signal　and　magnetic　noise.　Finally,　the　magnetic　signal　strengths　of　each　gear　tooth　root　are　extracted　using　cycle　average　and　local　statistic　method.　The　results　of　Experiments　show　that　the　method　is　suitable　to　pick　up　effective　ingredients　of　signal　to　extract　signal　feature　and　has　important　application　value　in　potential　fault　diagnosis　of　low　speed　and　heavy　load　gearbox.　©　(2013)　Trans　Tech　Publications,　Switzerland.