Abstract: The fluid flow phenomenon in the tundish influences strongly not only on homogenization of the composition and the temperature, but also on separation of the nonmetallic inclusions. Based on the dimensionless Froude and Reynold number similarity criteria, the effect of the gas blowing on the fluid flow in the tundish is studied in a water model. The velocity of liquid stream is recorded by a high speed camera. and the residence time distribution curves of the flow are measured.The experimental result shows that the gas blowing is beneficial to the separation of nonmetallic inclusions.