Detection　of　micro-cracks　before　assembling　has　always　been　a　challenge　in　gear　defect　detection.　A　mature　detection　method　of　micro-cracks　is　not　available.　Due　to　the　complex　detection　environment　and　large　production　of　gears,　it＇s　urgent　to　develop　a　rapid　and　accurate　detection　method　of　gear　micro-cracks.　It＇s　the　key　to　separate　and　extract　weak　vibration　signals　accurately　under　complex　disturbances　in　gear　defect　detection.　In　this　study,　vibration　characteristics　of　gear　defects　under　resonance　conditions　were　firstly　explored　and　a　detection　method　of　gear　micro-cracks　was　proposed　based　on　tuned　resonance.　Based　on　the　amplification　effect　of　tuned　resonance　on　the　peak　frequency　spectrum　of　gear　vibration,　meshing　frequency　and　sideband　frequency　characteristics　of　the　gear　defect　signal　spectrum　were　experimentally　investigated.　The　amplitudes　of　gear　meshing　frequency　and　its　harmonic　meshing　frequency　in　the　signal　frequency　domain　diagram　were　higher　and　the　surrounding　sideband　frequency　components　were　clearer.