With the developments of science and technology, the performance of steel is required strictly and the quality of steel needs to improve continuously. In continuous casting process, there is an important flow phenomenon when the molten steel flows from ladle to tundish. It is that the rapidly rotating free surface vortex will form as the liquid level descending continuously. The surface vortex can cause the slag entrainment. In order to suppress slag entrainment by vortex during the steel teeming process, and to improve the cleanliness and quality of steel, the movement process of vortex and variation of flow field are studied through both numerical simulation and water model experiments. Since the eccentricity (eccentricity is the ratio of the nozzle distance and the ladle radius) has a large effect on the vortex formation, the vortex movement and flow field variation at different eccentricities are analyzed in details. And the mechanism of vortex suppression is found. It is that disturbing the velocity distribution of vortex formation or/and decreasing the tangential velocity value can suppress the movement and development of vortex. Thus the critical height of vortex can be decrease and the vortex can be availably suppressed. And then a method of vortex suppression is proposed according to this mechanism of vortex suppression. The method by blowing gas at the bottom of ladle is proposed. And the optimal gas flow rate and gas nozzle position are obtained.