Abstract: The axial-torsional fatigue experimentation at 650℃ was carried out on notched specimens made of GH4169 super alloy, which is used for turbine of aeroengine. The stress-strain fields around the notch under both proportional and non-proportional loadings were analyzed by means of ANSYS software, and the fracture-prone points on the specimens were given. A new multiaxial damage parameter was proposed and the corresponding fatigue life prediction model was set up by the use of critical plane method. The results confirm the validity of the model given in this study by comparing the predicted fatigue life with the experimental life.