This study established a mathematical model of fluid flow phenomena for the liquid bath in smelting reduction processes by the CFD (Computational Fluid Dynamic) software PHOENICS. The SEM (Scalar Equation Method) model was employed to treat the multi-phase flow, viz. liquid metal and injection gas. The Chen-Kim k-e turbulent model which is suitable for gas-stirred system was imposed. An index named Mixtrg was defined to evaluate the mixing level of the injection gas to the liquid bath. The accuracy of the model was verified by comparing the theoretically predicted vertical velocity with the experimental data for the bubble-stirred air-water ladle.Based on the standard operational condition, the influence of operational variables of simulated vessel was studied for the flow patterns of liquid bath. The calculated flow patterns of bath were helpful for understanding about distribution of injection gas, flow patterns of liquid bath, wave motion of liquid bath surface and the erosion conditions near the wall of furnace.