Abstract: The failure influence factors of steel balls and the types and characteristics of common defects were summarized. The reasons for the failure of bearing steel balls were analyzed by means of macroscopic observation, micro morphology analysis, hardness test, chemical composition analysis, hot pickling test, pole stress test and so on. The results show that the process of steel balls manufacturing, subsequent storage and using process all affect the quality of the steel balls, and then influence the life of the steel balls, finally affect the life of the rolling bearing. In the case analysis, the tempering stability of the steel balls was not qualified because of the insufficient tempering time, Moreover, there existed excessive reticulated carbides, resulted in relatively low load-bearing capacity and fractured.