The　dynamic　characteristics　of　the　mill　and　the　drive　system　are　mutually　coupled　and　affected　closed-loop　system.　However,　most　research　has　considered　only　the　vibration　of　the　drive　system　or　the　vibration　of　the　mill　to　determine　the　cause　of　the　accident　in　the　equipment　condition　monitoring　and　fault　diagnosis　process.　Condition　monitoring　and　fault　diagnosis　based　on　this　type　of　approach　can　lead　to　misdiagnosis　or　missed　diagnosis　in　determining　faults　in　actual　systems.　So,　in　this　study,　a　dynamic　model　of　the　coupling　between　a　mill　and　its　drive　system　was　developed　to　study　the　interaction　of　the　mill　and　the　drive　system　with　the　goal　of　increasing　the　accuracy　of　diagnostic　methods　and　to　improve　the　quality　of　the　rolled　material.　A　nonlinear　coupling　dynamic　model　was　formulated　to　represent　the　relation　between　the　gearbox　vibration　amplitude　and　various　time-varying　parameters　to　study　the　effects　of　various　parameters　on　the　drive　system　vibration　characteristic　under　unsteady　lubrication.　Simulations　results　showed　that　increasing　the　strip　speed,　the　input　strip　thickness,　or　the　output　strip　thickness　or　decreasing　the　lubricating　oil　temperature　or　the　roller　radius　caused　the　vibration　amplitude　of　the　drive　system　to　increase.　The　vibration　frequency　caused　by　variations　in　the　strip　inlet　or　outlet　thickness　can　be　transmitted　to　the　drive　system,　and　gear　meshing　frequency　of　the　gearbox　can　be　transmitted　to　the　mill.　Test　data　from　an　actual　cold　rolling　mill　verified　the　accuracy　of　the　model.　The　model　was　shown　to　be　capable　of　simulating　the　mutually　coupled　and　affected　mechanism　between　a　mill　and　its　drive　system.