Aiming at the problems of low inclusion removal efficiency and large temperature fluctuations caused by the uneven flow field of the 5-strand tundish in Huaigang Steel， the tundish dam wall was redesigned. Compared with the original scheme， the overall shape of the dam wall remained unchanged， and the main optimizations were made to the position， aperture and inclination angle of the diversion holes. CFD simulation and industrial tests confirmed that： by opening the diversion holes on the side，reducing the hole diameter，and increasing the inclination angle， the response time of the 3rd strand increased by 89.1 s， the peak time increased by 160.3 s， the average residence time increased by 179.9 s， and the dead zone volume was reduced by 19.7%. The optimized flow field parameters enhanced the inclusion removal capacity by expanding the floating path and residence time of inclusions； relying on a more uniform flow field distribution， the temperature difference between the 1 st and 3rd strands was reduced from 3 ℃-5 ℃ to 0 ℃-2 ℃， verifying the regulatory effect of flow field uniformity on heat transfer processes. In the production of difficult-to-cast steel grades such as bearing steel， the fluctuation amplitude of the stopper rod in the 3rd strand of the optimized scheme was significantly reduced， and the qualification rate of inclusion inspection for high-grade special steel rolled products was increased from 95% to 98%， which confirmed that the flow field optimization has industrial-level stability and significance for improving the cleanliness.