A complete numerical solution for the micro thermal elastohydrodynamic lubrication (EHL) of planetary gearing in wind turbine gearbox is obtained with taking roughness effects and characteristics of non-Newtonian fluids into account. The oil film pressure profile, film shape and the trend of equivalent temperature rise in planetary gearing in special meshing points are drawn. Through comparing with lubrication performance in different surface morphology between Ra=0.8μm and 0.2μm, the results show that the film thickness ratio of ring gear and planetary gears with Ra=0.8μm is greatly smaller than 1.5. From the relationship between tooth surface damage and film thickness ratio, these gears are in abnormal lubrication state, surface damage, when Ra=0.8μm, can theoretically reach more than 15%. However, the surface damage ratio with Ra=0.2μm has been greatly deceased, so as to that it provides a theoretical basis of reliable lubrication analysis for wind turbine gearbox.