Abstract: A fatigue life analysis method for wind turbine main bearing with the type of three-row cylindrical roller and surface hardened raceways was established. Firstly,a 5-DOF mechanical model of three-row of cylindrical roller wind turbine main bearing was established in the Cartier coordinate system,and the internal roller load distribution of the bearing under the combined action of external loads in five directions was analyzed and calculated. Then,the elastoplastic contact finite element model between the cylindrical roller and the surface hardened raceway was established,and the pulsating stress distribution under the raceway surface caused by the roller contact load was calculated. Finally,the pulsation stress amplitude was converted into alternating stress amplitude by using Goodman equation,and Basquin stress-life theory was used to calculate the fatigue life of wind turbine main bearing. The results show that the downwind outer ring raceway of the bearing bears the thrust load from the wind rotor and has the shortest fatigue life,while the radial outer ring raceway bears the gravity load of the wind rotor and has the longest fatigue life. The fatigue life of the bearing depends on the downwind raceway.