An integral approximation solution of heat transfer in the grinding process is presented in this paper. Heat transfer models for the abrasive grain, fluid and workpiece were developed by using the integral approximation method. For the case in which film boiling does not occur in the grinding zone during the grinding process, the workpiece background temperature rise calculated by the present model agreed very well with previous theoretical analysis. The present model can also correctly simulate the grinding process when film boiling occurs in the grinding zone. Furthermore, a simplified model, which is applied only for cases where film boiling does not occur in the grinding zone, has also been developed.