Abstract: An elasto-plastic model for the thermal stress during solidification in strand is applied to the horizontal continuous casting of steel in Maanshan Iron and Steel Company. Calculation and analysis of the heat transfer, stress and strain for the strand have been made. The distribution of thermal stress for strand has been quantitively given. It has been indicated that because the surface reheating of stand is very large after the strand leaves the mould, the internal cracks will be formed.