In order to get a better inner quality of continuously cast steel slabs, insulated sprayed roll technique by using a ceramic material has been developed to increase the slab thermomechanical rigidity against the thermo-mechanical stresses. The idea behind this technique is to increase the slab solid shell resistance "Ic" by optimizing the homogeneity of cooling conditions between a pair of rolls. This is by minimizing a rapid fluctuation in the surface temperature between rolls especially at roll contact area. The mathematical model of thermal, solidification, solid shell resistance and cooling conditions has been developed. The model predications indicate that the increasing in the thickness of this layer "δC" or decreasing its thermal conductivity "κC" is proportional to decreasing the surface temperature peak at roll contact area. The predications also point out that the improving of the solid shell resistance depends on the optimum selection of δC and κC with cooling conditions between rolls. Also, the predications were used to explain and discussed the mechanism of characteristics of insulated layer with Ic and thermomechanical rigidity of steel slab.