The　multiaxial　fatigue　behavior　of　the　notched　specimens　and　thin　wall　tube　specimens　of　GH4169　super　alloy　was　investigated.　Symmetric　axial-torsional　strain　was　controlled　in　fatigue　tests　at　a　high　temperature　of　650°C　by　using　a　MTS　809　tension-torsional　servo-controlled　electro-hydraulic　testing　machine　with　proportional　and　non-proportional　loading.　The　phases　between　axial　strain　and　torsional　strain　were　0°　in-phase　(proportional)　and　45°,　90°　out-of-phase　(non-proportional)　respectively.　Based　on　the　critical　approach,　a　model　for　multiaxial　fatigue　life　prediction　was　established　by　combining　maximum　shear　strain　and　normal　strain　on　the　critical　plane,　and　the　effect　of　stress　state　under　the　multiaxial　cyclic　loading　condition　on　the　fatigue　life　was　taken　into　account.　The　results　of　life　prediction　show　that　the　new　fatigue　life　prediction　model　is　validated　with　the　experimental.