A　thermo-mechanical　coupling　model　for　a　rigid　flat　plane　and　an　elastic-plastic　rough　surface　based　on　three-dimensional　fractal　theory　is　established.　The　model　considers　the　elasto-plastic　deformation　of　the　rough　solid,　the　interaction　between　asperities,　and　the　heat　flux　coupling　between　the　sliding　surfaces.　By　using　the　finite　element　method,　the　frictional　sliding　process　of　the　rough　surface　and　the　flat　plane　is　simulated.　The　plastic　deformation　varied　with　depth　on　the　contact　asperity　of　the　rough　solid　are　analyzed.　The　numerical　results　from　the　analysis　and　simulation　show　that　the　equivalent　plastic　strain　on　the　frictional　contact　surface　layer　increases　obviously　when　the　relative　sliding　velocity　changes　suddenly　and　the　instantaneous　flash　temperature　emerges.　On　this　frictional　contact　surface　layer,　through　the　different　contact　asperity,　the　distribution　of　the　plastic　deformation　varied　with　the　depth　is　different.　The　maximum　equivalent　plastic　strain　may　be　located　on　the　contact　surface　or　in　some　depth　under　the　contact　surface.　These　results　are　validated　by　experimental　observation　results　available　in　the　literature.　The　experimental　results　are　obtained　by　studying　the　surface　layer　deformation　photograph　of　the　metal　after　the　dry　friction.　The　plastic　deformation　on　the　frictional　contact　surface　layer　accumulates　during　the　frictional　sliding,　which　will　result　in　the　micro-hole　and　the　crack　source　around　the　micro-defects　on　the　contact　surface　layer.　©2014　Journal　of　Mechanical　Engineering