Abstract: A thermal resistance network model was established for the high-speed end bearing of a wind turbine gearbox, based on which dynamic thermal characteristics of the bearing were studied at varying wind speeds and loads. Ansys Workbench finite element method was used for three dimensional thermal-stress coupling analysis to simulate the temperature, deformation and thermal-stress characteristics of the bearing under fault conditions. Results show that the wind speed, the contact thermal resistance between inner ring and roller element of bearing as well as the convective thermal resistance of oil would significantly influence the bearing temperature. In the case of normal bearing operation, the maximum deformation occurs at the contact surface between inner ring and roller element, while the maximum stress occurs at the edge of outer surface of outer ring. When bonded and wear failures appear to the bearing, its temperature distribution, heat flux and thermal stress would change in different degrees.