The spreading properties of unsteady state temperature wave, heating flux wave and heating shock phenomena during continuous hot slab rolling have been numerically simulated for three types of commonly used composite rolls by use of various coordinate systems and user–defined functions based on Fluent 6.3 software. The results indicate that the temperature wave can be divided into a high–frequency and low–frequency unsteady state temperature wave to describe the temperature distribution and spreading properties in rolls. It is found that the wave amplitude of the high–frequency temperature wave will quickly decrease with the increase of propagation depth, and its propagation depth of maximum impact is less than 7.5 mm. But, under the same rolling conditions, the amplitude attenuation of the low–frequency temperature wave is slower, and its propagation depth of impact is more than 20 mm. The heating shock decreases rapidly with the increase of distance from the surface of work roll. The heating shock depth is the deepest for the high speed steel composite roll, but the shallowest for the high nicked chromium cast iron composite roll under the same rolling conditions. The absorbed and resided heat by work–rolls during each slab hot rolling is down, but the dissipated heat by rolls is up with rolled slab number increasing.