Abstract: Investigation on the possibility of the improving the refining efficiency by applying swirling flows in the up-leg of RH refining process, the swirling flows are produced by using the impeller with the six plane blades and axial flow impeller. Difference of gas-liquid flow phenomena between without and with the swirling flow is analyzed using the water model experiments. The ultrasonic flowmeter is used to measure the circulation flow rate. A video recorder is used to record the two-phase flow patterns. The water model experiments show that the circulation flow rate with swirling flow increases significantly. Caused by the centripetal force, the gas bubbles and the inclusions, whose densities are smaller than that of liquid, concentrated on the central zone of the up-leg. Where the collision and the coagulation of the bubbles and the inclusions can be increased remarkable. The attachment of the bubbles on the inner walls of the up-leg of RH vessel is also avoided. Thus the life of the RH vessel can be improved.