A numerical thermoelastohydrodynamic simulation method is proposed in this article with the considerations of the topography of sealing lip and shaft, interference of sealing lip, the elastic deformation of sealing lip and the influence of temperature on the viscosity of lubricant. The proposed method is applied to WR auto water pump bearing seal to study the lubrication and sealing property of lip seal, and the relationships between the lubrication property of lip seal and interference, rotation speed in given working condition are obtained.