Many mechanical components experience a multi-axial random loading in their service life, which could lead a fatigue failure. Nowadays, to overcome the lack of appropriate testing setup, the assessment of structural integrity of the components is performed by several testing procedures like loading alongside different axis in sequential manner, specific test setup or particularly geometry of the specimens. The objective of this research is to develop an equivalent single-axis random excitation system estimation model to predict the life of multi-axial loaded random fatigue system.