Abstract: A method for determining load distribution in yaw bearing of wind turbine using coordinate transformation principle is presented because the analysis procedure for standard bearings can not be used to decide the properties of large scale, complex load conditions of yaw bearing. In order to evaluate the outer loads acting on the yaw bearing, a coordinate system is first established in wind turbine which is used to transmit the loads from the roots of blades to the outer ring of the yaw bearing using coordinate transformation method. Thus the loads acting on the outer ring can be formulated as a function of the motion parameters - such as the rotation of rotor, blade incidence and the angle of rotor shaft - of wind turbine. Then, two coordinates are established on the inner and outer ring, and the static equilibrium equation of yaw bearing is established by expressing the contact elastic deformation as a function of the relative movement parameters of these two coordinates. A calculation example under three load conditions is then presented. The results show that the contact load distribution in the yaw bearing coincides with a sine curve, and the turnover moment has the greatest effect on it.