Abstract: Bearings have a wide range of applications in wind turbine generator systems. The structure, type, failure mode and causes of rolling bearings were summarized, and the most frequently fatigue wear failure modes and mechanisms were analyzed and discussed. The effects of residual austenite, processing accuracy, metallurgical quality of materials and residual stress on the actual service life of bearing were discussed in terms of comprehensive test results and practical application effects. The application and failure characteristics of bearing on wind turbine generator systems were introduced. Another practical failure mode of bearing on wind turbine, hydrogen embrittlement or hydrogen embrittlement fatigue, was shown in actual cases, and some reasons were analyzed and discussed. The preventive measures for the failure of bearings on wind turbine generator systems were proposed.