Abstract: In order to improve the billet quality by optimizing fluid flow,uniforming the molten steel temperature of each nozzle and prolonging the average residence time of near nozzles,the unsymmetrical configuration tundish in works and two optimal designs were studied by means of numerical simulation.The fluid flow,heat transfer and residence time in the tundish were calculated.The results show that fluid flow and temperature distribution were unsuitable in the original tundish without flow control devices.The fluid flow and temperature distribution were optimized in the tundish with optimal configuration.The optimum configuration was settled by the calculation results.