Abstract: It is difficult to determine precisely the temperature field in plate rolling process to which the error of calculated result is too great with tiresome calculating procedure if using conventional temperature models. So, based on the heat transfer theory, a thermal balance equation as model is developed using the implicit difference method to simulate the temperature variation of plate core/surface in hot rolling and cooling processes for plate production. Some conclusions are thus reached: (1) the plate surface temperature decreases sharply during rolling, but it tends to increase in the interval between intermittent rolling passes. During cooling, the plate surface temperature decreases quickly. (2) The calculated plate surface temperature is in agreement with that measured and, therefore, the model is available to simulate the temperature variation in plate rolling process.