A model of heat transfer and solidification of continuous cast has been established, including boundary conditions in the mold and spray zones. A finite difference method was used for the numerical simulation. The model calculates the shell thickness and temperature distributions of the slab real time. The importance effect of non-linear material properties of specific heat and thermal conductivity as well as phase changes during solidification is treated. The adequacy of model has been proved by industrial and experimental data. The model can be applied to solve some practical problems in continuous cast.