As　crucial　indicators　of　stability　and　service　reliability,　dynamic　and　tribological　behaviors　of　gear-rotor　system　are　investigated　under　both　stationary　and　nonstationary　conditions　based　on　a　new　tribo-dynamic　modelling　approach.　In　the　global　dynamic　model,　the　shaft　compliance　is　considered　with　the　gyroscopic　effect,　and　the　dynamic　meshing　force　formulations　under　elastohydrodynamic　and　hydrodynamic　lubrication　states　are　integrated.　The　stepwise　coupling　strategy　is　developed　to　describe　the　two-way　interaction　between　vibration　and　lubrication　parameters　in　each　time　step.　The　methodology　is　validated　numerically　and　experimentally.　The　investigation　shows　that　high-speed　and　light-load　conditions　result　in　chaos,　accompanied　by　extremely　high　subsurface　stress.　Higher　additional　torque　during　the　acceleration　and　deceleration　brings　about　rotating　speed　oscillation　and　more　complex　frequency　components.　Faster　torque　fluctuation　contributes　to　multi-periodic　and　chaotic　motions.　The　non-monotonic　relationship　with　maximum　pressure　and　minimum　film　thickness　is　also　observed.　Disturbing　loads　in　the　forms　of　sudden　load　variation　and　random　load　disturbance　have　limited　impacts　on　system　tribo-dynamic　performance　generally.　The　methodology　and　results　provide　useful　guidelines　for　the　tribo-dynamic　design　of　gear-rotor　system.　©　2025　Elsevier　Ltd