Abstract: A model of temperature field was developed to describe the continuous casting process. The model of the non-physical boundary condition of temperature field was also proposed by extrapolation technique for the castings out of the mould to get efficient and accurate calculation results of the steady temperature fields. Then, the steady temperature fields of Al-Cu alloys in semi-continuous casting process were calculated using the given models, and the mesoscale temperature field thus determined was taken as the conditions for the simulation of liquid-solid phase transformation. The calculated temperature fields were applied to the multi-scale simulation of the solidification of the Al-10%Cu alloys at different pouring temperatures, thus obtaining the morphology and reasonably distributed grain structure. It was found that the simulated grain size and morphology of near liquidus cast ZL201 alloy is well consistent with experimental results. All the results show that the models developed for temperature field and non-physical boundary condition are applicable to the simulation of steady continuous casting process, especially they can provide correct data of temperature fields as reference for the multi-scale simulation of solidified metal structure.