Abstract: The effect of the additional cyclic hardening caused by the non-proportional loading is an important factor influencing fatigue damage for GH4169 superalloy under multiaxial variable amplitude loading.In this paper,the damage curve rule is modeled using the fatigue damage model,which takes into account not only the effect of the additional cyclic hardening caused by the non-proportional loading,but also the elastic-plastic stress state of material during the cyclic loading process.The model allows the non-linear effect of loading model and amplitude on fatigue damage at different load levels,also considers the effect of non-proportional loading,and does not include the material constants.The fatigue test data for GH4169 super alloy have been used to verify the model.Resultsshow a good agreement for predicting fatigue damage under complicated multilevel loading.