A water modeling approach was employed to investigate the effects of gas injection condition on the fluid flow in a two-strand tundish. The rational parameter of argon injection was determined as the optimized positions. Adopting the Case of weir-gas-dam could prolongs fluid’s retention, stagnation and peak periods in the tundish properly. The dead zone could be reduced to 17.4%. The flow pattern which was oberved with ink showed that the flow condition was improved greatly in Case 2(WGD), favoring the mixture of liquid steel and the inclusion removal.