Based　on　the　principle　of　critical　plane　approach,　a　multiaxial　fatigue　damage　model　is　proposed　in　this　paper,　which　can　be　applied　to　axial-torsional　loading.　Three　parameters　on　the　critical　plane　are　considered　in　this　model,　which　takes　into　account　not　only　the　maximum　shear　strain　range　and　normal　strain　range　on　the　critical　plane,　but　also　the　effects　of　the　additional　cyclic　hardening　caused　by　the　non-proportional　loading　and　the　mean　stress　on　the　fatigue　life.　Additionally,　its　accuracy　for　life　evaluation　is　relatively　high,　and　it　is　convenient　for　engineering　application　because　of　no　material　constants.　The　capability　of　fatigue　life　prediction　for　the　proposed　fatigue　damage　model　is　verified　by　the　experimental　data　from　constant　amplitude　axial-torsional　loading　of　Inconel　718　steel,　GH4169　alloy,　and　Haynes　188　superalloy.　Prediction　results　agree　well　with　the　experimental　results.