The invention relates to a large wind turbine unityaw motor selection method and a driving torque determination method. The driving torque determination method comprises the following steps: building a wind turbine unitsimulation model, and solving external applied load, capsizing moment, axial force and radial force on a yaw bearing as well as rotating speed and acceleration of the yaw bearing in an extreme condition; according to the parameters, calculating racewayfriction moment of the yaw bearing; building a mechanical model in a unit yaw process, and solving driving torque of ayaw motor in the yaw process. The selection method comprises the following steps: according to the driving torque of the yaw motor at each time point, calculating an effective value and a greatest effective value of the driving torque of the yaw motor in a fatigue condition, determining a rated value of a to-be-selected yaw motor, and selecting a yaw motor according to the rated value and a driving torque peak value Mp. The large wind turbine unityaw motor selection method and the driving torque determination method are simple in principle and easy for operation, the precision is high, a unit is high in safety and reliability, clamping load of a yaw brake is effectively lowered, abrasion of a yaw brake pad is reduced, a yaw maintenance period is prolonged, and the maintenance cost of the unit is lowered.