Abstract: An estimation method for the fatigue life of notched specimen under multi-axial loading is proposed. The multi-axial fatigue damage parameter in every part of notched specimen is calculated based on a critical plane criteria. The location of notched specimen with the maximum damage parameter is taken as a multi-axial fatigue dangerous point. The critical distance calculation methods of a hot point method and a line method are proposed based on a critical distance thought. The hot method and line method are taken to consider the effects of a damage gradient nearby the fatigue damage point of notched specimen. The modified damage parameter based on a critical distance is taken to calculate the multi-axial fatigue life of notched specimen. The method of estimation fatigue life is evaluated by the multi-axial fatigue tests of SAE1045 steel notched specimen. The result shows that the estimation method for fatigue life has good predictive ability. The prediction results are almost within a factor of three scatter bands of test results.