Abstract: An optimization of flow control "devices in a 40-t single strand continuous casting tundish was carried out by water modeling experiments and industrial experiments. Three cases were considered during the experiments, i. e, tundish equipped with a turbulence inhibitor, tundish equipped with a turbulence inhibitor and dams, and tundish equipped with a turbulence inhibitor, dams and weirs. The results show that the dams play a much more important role than the weirs in improving the fluid flow characteristics and decreasing the dead volume fraction in the tundish. The average residence time increases firstly and reduces afterward with increasing distance between the dam and nozzle. The tundish equipped with a turbulence inhibitor and dams is the optimized according to these results, and the dead volume fraction reduces to 13.6% from 25.9%. The results of industrial application shows that the T. O and N contents reduce greatly and the mass fraction of macro inclusions in normal slabs reduced to 3.2×10^-7 from 8.4 × 10^-7.