In this paper, a transient temperature calculation model for simulating grinding face gear with a grinding worm is proposed. Firstly, according to the principle of differential geometry, the equations for determining contact arc length and contact width of the instantaneous grinding area between the worm grinding wheel and the face gear are deduced. Based on the method for the single abrasive particle cutting force and grinding heat, a mathematical model for the grinding force and grinding heat of the face gear is established, and the theoretical calculation formula of the instantaneous maximum temperature for grinding teeth of the face gear is obtained. Secondly, a finite element model of temperature field for face gear grinding with moving heat load of grinding worm wheel is established, and the influence law of grinding process parameters on tooth surface temperature is studied. Finally, the validity of the temperature field simulation model is verified by multi-group temperature testing experiments for face gear grinding.