An estimation method for fatigue life under multi-axial random loading was proposed.Firstly the rain-flow counting method was used to identify shear strain cycles on each plane.The shear strain cycles were taken as a main control parameter of multi-axial fatigue damage.Then the maximum normal stress and normal strain range within each shear strain cycle were calculated as the second damage control parameter.The damage of each plane was calculated by multi-axial fatigue life model and the critical plane was identified as the plane with the maximum damage.The fatigue life was determined using the damage associated with the plane.The method for fatigue life under multi-axial random loading was evaluated and validated by the multi-axial random fatigue test datum of SNCM630 steel

304 stainless steel and S45C steel.The multi-axial random fatigue life prediction results of these materials are almost within a factor of two scatter band of the test results.