Abstract: Based on the design and technology parameters of four-hole oxygen lance applied in an steelmaking workshop,influence of orifice spacing,lance level and syncretizing length on the impact area of molten bath under gas jet sprayed from non-variable angle and variable angle four-hole oxygen lance were simulated by Fluent software.It is showed that the impact area of molten bath under gas jet sprayed increase to the summit and then decline with the increasing of the lance level.From the view of effective impact area of molten bath,the lance level should be controlled within the lance height at which the maximum effective impact area can achieved.The influence of syncretizing length on the impact area of molten bath is significant,the impact area of oxygen jet to molten bath increase with the increasing syncretizing length and the drift distance of central line.The impact area of molten bath decline with the decrease of the orifice spacing.The fluctuation of flow speed increase with the increasing of orifice spacing,reducing the orifice spacing can make the speed stable quickly.The impact area of molten bath by variable angle oxygen lance are considerably larger than that by non-variable oxygen lance at the same lance level.