Abstract: In the converter steelmaking process,oxygen lance position is adjusted to realize slagging,decarburization,heating and stirring. The effect of oxygen lance position on molten pool flow was studied when blowing by a four-hole supersonic oxygen lance in a 100 t converter. It is found that low lance position has significant benefit to increase the impact depth and the flow velocity of molten steel at the surface,but high lance position is in favor of enlarging the jet flow impact area,improving the uniform velocity distribution of molten steel in the radial direction and increasing the flow velocity of molten steel at the furnace bottom. When the lance position increases from 1.2 m to 1.8 m,the impact cavity of the slag layer enlarges from 2.119 m to 2.645 m and the impact depth of jet flow decreases obviously.