Abstract: Hydraulic model and numerical simulation had been utilized to study the behavior of single strand tundish field of high speed casting tinplate.RTD curves had been obtained through the hydraulic model using impulse response method.The curves had been used to analyze the flow patterns of the tundish.The numerical simulation had been carried out by a Fluent commercial software to simulate tundish field and inclusion formation.Based on the RTD curve and simulation results a optimized casting plan had been established.The average residence time of the liquid steel has extended from 340.7 s to 545.3 s,increasing by 60.1%,while the dead zone volume ratio has decreased from 46.0% to 13.6%,reducing by 70.4%.With the help of modified casting process,the removal rate of micro inclusions and endogenous inclusions in the tundish has increased significantly.