A　fatigue-oxidation-creep　damage　model　that　can　take　into　account　the　effect　of　multiaxial　cyclic　feature　on　the　damage　mechanism　is　proposed　under　axial-torsional　thermo-mechanical　fatigue　loading.　In　the　proposed　model,　the　effects　of　non-proportional　additional　hardening　on　fatigue,　oxidation,　and　creep　damages　are　considered,　and　the　variation　of　oxidation　damage　under　different　high　temperature　loading　conditions　is　also　described.　Moreover,　the　intergranular　creep　damage　needs　to　be　equivalent　to　the　transgranular　damage　before　accumulating　with　the　fatigue　and　oxidation　damages.　The　fatigue,　oxidation,　and　creep　damages　can　be　expressed　as　the　fractions　of　fatigue　life,　critical　crack　length,　and　creep　rupture　time,　respectively,　which　allows　the　linear　accumulation　of　different　types　of　damages　on　the　basis　of　life　fraction　rule.　In　addition,　the　proposed　model　is　validated　by　various　fatigue　experimental　results,　including　uniaxial　thermo-mechanical　fatigue,　axial-torsional　thermo-mechanical　fatigue,　and　isothermal　axial-torsional　fatigue　under　proportional　and　non-proportional　loadings.　The　results　showed　that　the　errors　are　within　a　factor　of　2.