The bearing life analysis under the random multiaxial loading was the very complex, the key was to get the exact stress distribution. Therefore, the stress analysis was carried out for the main shaft bearing of an aviation motor. Firstly, based on the characteristic of air motor axis bearing, the Von Mises stress distribution model of the random multiaxial loading was built up under the axial, sailing and vertical direction power spectrum density. Secondly, the modal with prestress analysis and random vibration analysis were carried out through Ansys Workbench. Finally, the mean value of the stress was compared. The correctness stress analysis method was validated, which lays the basis for the bearing fatigue life analysis.