Abstract: Through physical and mathmaterical simulation,the flow patterns in the tundish with a new-born type of flow control device——Preventur Pad were studied. Compared with the typical dams and weirs,preventur pad can return the fluid from the stockel directly to itself,maximize the mean and minimum residence times,increase plug volume and cancel short circulation in the tundish.Especially in high-speed casting, preventur pad+dam+weir has better effect on the removing of inclusions from the tundish. The fluid patterns in the tundish with preventur pad have been proved through mathematical simulation.