Abstract: The heat transfer model of the rotating ring and the stationary ring of mechanical seal was built.The method to calculate the frictional heat that transferred by the rings was given.The coupling analysis of the frictional heat of fluid film and thermal deformation of end faces was carried out by using FEA and BP ANN,and the relationship among the rotational speed ω,the fluid film thickness h_i on the inner diameter of sealing face and the radial separation angle β of deformed end faces was obtained.Corresponding to a given ω,h_i and β can be obtained by the equilibrium condition between the closing force and the bearing force of fluid film.The relationship between the leakage rate and the closing force was analyzed,and the fundamental of controlling the leakage rate by regulating the closing force was also discussed.