In　view　of　the　nanoscale　contact　behavior　of　head　disk　interface　at　present,　the　improved　GW　model　is　proposed　to　evaluate　micro　contact　force.　And　the　intermolecular　force　is　also　introduced　to　establish　the　contact　mechanical　model　of　the　head　disk　interface.　Then　the　two　degree　of　freedom　dynamic　model　is　performed　on　this　contact　mechanical　model.　The　dynamic　response　characteristics　of　head　under　different　contact　states　is　analyzed　by　Runge　Kutta　method.　The　results　demonstrate　that　when　the　flying　height　is　lowered　to　a　certain　value,　the　contact　will　induce　the　self-excited　vibration　of　the　head,　which　is　a　key　issue　that　affects　the　flying　instability　of　the　head.　To　verify　the　accuracy　of　the　head-disk　interface　contact　dynamics　model,　the　heads　with　the　same　physical　parameters　as　the　dynamic　model　are　selected　to　perform　the　dynamic　response　test　under　overload　condition.　It　shows　that　the　relative　error　between　the　theoretical　calculation　value　of　the　model　and　the　experimental　test　result　is　less　than　8%.　©　2022　Journal　of　Mechanical　Engineering.