Tooth surface temperature and its changes are main basis to calculate gear tooth deformation and to determine whether gluing or not. According to the basic principles of face-gear driving and heat transfer, analyzed the face gear meshing area. By means of surface temperature method, derived face-gear mathematical model of lubrication, oil film thickness equation and oil film energy equation, and established the face-gear transmission equations for calculating instantaneous contact temperature. Studied the contact stress of engagement、relative sliding velocity of tooth surface and the computing of friction coefficient between the tooth surface. Conducted a finite element analysis on the temperature rise at different positions in the face-gear meshing process. Researched the tooth surface temperature distribution to provide an effective theoretical basis for face-gear design.