Abstract: The article involves the experimental research with hydraulic simulation on the tundish of the CCM for round billets located in Pangang Group Chengdu Seamless Steel Tube Co., Ltd. Based on the similar theory, water was used to simulate the mobility characteristics of liquid steel in the tundish. According to the simulation result, the tundish dam was designed, and the distribution curves of liquid steel duration in the tundish and inclusion trapping rate under different designs were determined, and elements affecting the liquid steel in-tundish mobility and proper building-up of the dam analyzed.