The　bolted　joint　is　an　important　link　that　affects　the　accuracy　maintenance　of　the　heavy-duty　machine　tool.　Due　to　bolts　of　the　crossbeam　are　under　a　preload　of　several　hundred　kN　for　an　extended　period,　the　bolt　gradually　creeps　and　elongates　as　the　machine　tool＇s　service　time　increases.　This　relaxation　of　the　preload　results　in　a　degradation　of　the　bolted　stiffness,　weakening　the　dynamic　response　of　the　bolted　joint　system.　To　reveal　that　the　degradation　law　of　crossbeam　bolting　performance　of　the　heavy-duty　machine　tool　induced　by　bolt　creep,　based　on　the　NortonBailey(NB)　model,　a　method　for　analyzing　the　creep　of　bolts　with　precision　threads　is　proposed,　and　the　influence　of　thread　geometry　and　friction　coefficient　on　the　creep　stress　relaxation　of　bolts　is　studied.　Considering　the　interface　contact,　an　interface　contact　stiffness　model　is　derived　based　on　fractal　theory.　The　dynamic　equation　of　the　bolted　beam　system　is　established　using　the　Matrix27　stiffness　matrix.　The　dynamic　response　of　the　bolted　system,　resulting　from　the　degradation　of　interface　stiffness　due　to　bolt　creep,　is　analyzed.　The　results　show　that　the　stress　relaxation　of　bolt　creep　is　not　only　related　to　creep　parameters,　but　also　related　to　the　mate-thread　interaction.　The　dynamic　model　with　Matrix27　stiffness　matrix　is　comparable　to　experiment　in　calculation　accuracy　and　efficiency,　which　provides　technical　guidance　for　machine　tool　dynamics　analysis　and　effectively　solves　the　scientific　problem　of　beam　bolting　performance　degradation　during　the　service　of　heavy-duty　machine　tools.