Abstract: In this paper, a physical model with a 1∶4 similarity ratio was established to optimize the structure based on the three-strand tundish provided by a domestic steel plant. By installing the flow control device and adjusting both the upward elevation angle and the height of the diversion hole, multiple optimization schemes were designed with these two parameters as variables. The residence time distribution (RTD) curves and flow characteristic parameters for each scheme were obtained through physical simulation using the “stimulus response” method, allowing the optimal retaining wall structure of the tundish to be selected. Then, the optimization effect was evaluated under different drawing speeds. The experimental results show that at a flow rate of 9.88 L/min, the percentage of dead zone decreases from 25.4% to 4.4% after optimization. At the same time, the average residence time increases from 317 s to 406 s, and the standard deviation of residence time decreases from 24.75 to 5.44. At a flow rate of 6.41 L/min, the percentage of dead zone decreases from 29.5% to 5.4% after optimization, the average residence time increases from 463 s to 620 s, and the standard deviation of residence time decreases from 22.4 to 3.77. These results indicate a significant improvement in the flow field of the tundish under different working conditions, providing theoretical guidance for tundish design.