Abstract: A two dimensional coupled model of fluid flow and heat transfer of liquid steel and water in a mold was established to investigate the influence of inlet cooling water temperature and velocity on the mold tube temperature field and average mold heat flux.Solved by Fluent,this model simulated the flow and heat transfer of liquid steel and cooling water,solidified shell growth,and heat transfer across air gap and mold fluxes by conduction and radiation. The model's accuracy was verified by comparing the shell thickness and copper tube temperature field with other researches. Model results suggest that the inlet cooling water temperature notably affects the cold face temperature of the copper tube. If the inlet cooling water temperature exceeds 313 K,the highest temperature of the cold face will surpass the boiling point of water. However,an increase of 0.49 m·s^-1 in water velocity can diminish the adverse effects of an increase of 4 K in inlet cooling water temperature.