With the increasing demand for clean smelting of complex copper containing resources in China, oxygen bottom blowing copper smelting technology is playing an important role, and higher requirements are being put forward for its core equipment's (bottom blowing furnace) smelting capacity. Compared with other bottom blown furnaces, large oxygen bottom blown furnaces have larger specifications and more complex structures, and a high degree of matching between structure and function will be a very important issue. The position of the oxygen lance area is an important factor affecting the fluid flow and mass transfer inside a large oxygen bottom blowing furnace, thereby having a significant impact on the smelting effect. This work takes a large-scale copper smelting oxygen bottom blowing furnace of a certain enterprise as the research prototype, and uses numerical simulation methods to study the influence of the position of the oxygen lance on the flow characteristics of the large-scale oxygen bottom blowing furnace. The main focus is to investigate the influence of the position of the oxygen lance on the functional area and flow field inside the furnace. The results indicate that adjusting the position of the oxygen lance area can alter the distribution pattern of the functional areas inside the furnace. The "one end reaction and one end settlement" mode results in an asymmetric distribution of functional areas within the furnace. The effective extension of the settlement zone is conducive to the full separation of slag and matte. Offsetting the oxygen gun area towards the copper discharge port by 2300 mm form a "reaction at one end and settling at the other" mode. The settling area in front of the slag port is extended by 53.74%, and copper matte and copper slag achieve a more comprehensive and reasonable transition, full separation, and can be used as a directional control measure to optimize production.