The　severe　wear　of　separating　ring　is　considered　to　be　a　main　reason　which　leads　to　the　improper　declutch　of　the　main　clutch　of　heavy　vehicles.　The　wear　mechanism　of　the　separating　ring　is　not　well　understood.　Scanning　electron　microscopy　and　transmission　electron　microscopy　were　employed　to　analyze　the　surface　features　and　dislocation　characteristics　of　the　separating　ring.　The　typical　features　of　furrows　and　rolled　tongue-like　metal　were　found　on　the　surface　of　separating　ring　by　scanning　electron　microscopy　observation,　which　can　be　considered　as　a　major　indication　of　the　grain-abrasion.　A　zone　of　high　density　dislocation　was　noted　on　the　subsurface　of　the　separating　ring　by　transmission　electron　microscopy　observation,　which　implies　the　contribution　of　the　severe　impact　on　the　surface　of　the　separating　ring　in　the　wear　process.　The　influences　of　the　structure　of　the　separating　ring,　the　service　condition　and　the　in-service　stress　distribution　on　the　wear　behavior,　were　also　analyzed.　The　results　show　that　the　failure　of　separating　ring　results　from　the　impact　wear　and　grain-abrasion　together　with　the　plastic　deformation.