Abstract: A four-strand L type tundish in the steel plant of Xinxing Ductile Iron Pipes Co., Ltd., was studied.On the basis of similar principle, a 1:2 physical model of four-strand caster tundish was built.The simulating study shows that the internal structure of the prototype tundish was unreasonable, existing a large dead zone, the largest dead area ratio was 66.2%;There was a large difference in flow characteristics exiting between the four outlets of the tundish.So the original design of the tundish can not meet the technical requirements for inclusion floatation and temperature homogenization.Among all kinds of optimization cases, "baffle+single-blowing" (case C) and "baffle+single-blowing+turbulence inhibitor" (case D) are ideal optimization cases.Case D has the smallest dead zone proportion and the longest average residence time, with the dead zone proportion 19.7%, dropping 15.2% than the prototype, and the average residence time was 433 s, increasing 83 s than the prototype.