Abstract: The fluid flow of four-strand tundishes under two different control devices was studied by water model experiments and numerical simulation. The results show that the formation of short-circuit flow in the original tundish makes liquid steel have short residence time in the middle outlet, and have large difference of residence time compared with the edge outlet. The improved tundish can homogenize the residence time of molten steel between different outlets, decrease the dead volume fraction, and increase the removal rate of inclusions. The plant trial shows that the macroinclusion content and the microinclusion number in billet decrease by 44.9% and 2.7%, respectively, compared with those of the original tundish.