Abstract: The outer ring raceway surface of a certain type of aviation rolling bearing had spalling. By means of macroscopic observation, metallographic examination, immersion ultrasonic testing, hardness testing and scanning electron microscopy analysis, the causes of the bearing outer ring spalling were analyzed. The results show that the bearing outer ring raceway had contact fatigue spalling, which was caused by the existence of small defects in the material and the formation of a high hardness “butterfly” organization under the action of cyclic stress, which accelerated the bearing outer ring fatigue spalling.