The　durability　of　mechanical　structures　such　as　gears,　bearings　and　seals　relies　on　the　integrity　of　the　liquid　layer　separating　the　contact　surfaces.　Traditional　ultrasonic　pulse-echo　method　has　low　time　resolution　and　it　is　difficult　to　measure　the　thickness　of　the　thin　layer;　and　the　measurement　result　of　ultrasonic　measurement　with　piezoelectric　transducer　is　easy　to　be　influenced　by　the　contact　condition　between　the　piezoelectric　transducer　and　specimen.　In　this　paper,　an　electromagnetic　acoustic　thickness　measurement　method　for　thin　liquid　layer　based　on　singularity　extraction　with　wavelet　transform　is　proposed.　Meanwhile　the　influence　of　different　wavelet　basis　functions　and　scale　extents　on　singularity　extraction　for　ultrasonic　echo　signal　of　thin　liquid　layer　is　investigated;　and　the　optimal　wavelet　basis　functions　and　scale　extents　suitable　for　the　thickness　measurement　of　thin　liquid　layer　are　obtained.　Experiment　results　indicate　that　the　electromagnetic　acoustic　testing　method　based　on　singularity　extraction　with　wavelet　transform　can　achieve　the　thickness　measurement　of　thin　liquid　layer　nicely.