Abstract: Some mathematical models were developed for preheating the core of composite roll for continuous casting, then the effects of the casting speed and ceramic heat-insulation tube on the distribution of preheating temperature were investigated by numerical simulation. The results indicated that the maximum temperature difference between roll core's surface and center appears when the core is drawn up to equivalent to the bottom of coil, and the center temperature is higher than surface's when it goes off to distance from the position because of the heat radiation of core's surface. The high casting speed is disadvantageous to roll core reheating. The ceramic heat-insulation tube will benefit the heat preservation of core's surface when the casting speed is low but it is not so obvious at high casting speed.