The　multiaxial　thermomechanical　fatigue　properties　for　nickel-based　superalloy　GH4169　in　aeroengine　turbine　discs　are　investigated　in　this　paper.　Four　types　of　axial-torsional　thermomechanical　fatigue　experiments　were　performed　to　identify　the　cyclic　deformation　behavior　and　the　damage　mechanism.　The　experimental　results　showed　that　the　creep　damage　can　be　generated　under　thermally　in-phase　loading　while　it　can　be　ignored　under　thermally　out-of-phase　loading,　and　the　responded　stress　increasing　phenomenon,　that　is,　non-proportional　hardening,　can　be　shown　under　the　mechanically　out-of-phase　strain　loading.　Based　on　the　analysis　of　cyclic　deformation　behavior　and　damage　mechanism,　a　life　prediction　method　was　proposed　for　multiaxial　thermomechanical　fatigue,　in　which　the　pure　fatigue　damage,　the　creep　damage,　and　the　interaction　between　them　were　simultaneously　considered.　The　pure　fatigue　damage　can　be　calculated　by　the　isothermal　fatigue　parameters　corresponding　to　the　temperature　without　creep;　the　creep　damage　can　be　calculated　by　the　principle　of　subdivision,　and　the　creep-fatigue　interaction　can　be　determined　by　creep　damage,　fatigue　damage,　and　an　interaction　coefficient　which　is　used　to　reflect　the　creep-fatigue　interaction　strength.　The　predicted　results　showed　that　the　proposed　method　is　reasonable.