Abstract: In light of the structure and technics parameters of the three-strand 220 mm X 220 mm square billet continuous casting tundish in TISCO, fluid flow field and temperature field of the tundish are mathematically simulated with the software ANSYS FLUENT. The results show that the flow of prototype tundish is unreasonable, the short circuit flow and the dead zone exist in the No. 2 strand, and the similarity among the various stands is poor. The optimization schemes have formed weirs in the pouring area to form flow buffer zones. Thus the steel flow is redistributed. The flow field consistency has been greatly improved. After the optimal schema was applied to the site, the number of inclusions in the No. 1 and the No. 2 strand was reduced by 9.51% and 23.52% respectively, and the difference between strands was reduced by 52. 72%. The number of inclusions and the difference between strands were significantly reduced.