<p>The multi-lance top-blowing converting furnace is a critical component of the continuous copper smelting process, increasingly replacing conventional PS converters in China. However, the selection of furnace structure and the challenge of surface sloshing persist in the smelting process. This study utilizes a numerical simulation methodology, incorporating the volume of fluid interface tracking approach in conjunction with the realizable <i>k–ε</i> turbulence model, to address the complexities of interphase fluid within an industrial-sized multi-lance top-blowing copper converting furnace. After validation, the impact of furnace geometry on stirring efficiency, including velocity, turbulent kinetic energy, vorticity, and dead zones, as well as the dynamic behavior, energy transfer, and stability of the molten bath in the top-blowing process, are analyzed. At <i>U</i>_f = 0.05 m/s, the iso-surface spans most of the bath with low turbulent kinetic energy, while at <i>U</i>_f = 0.5 m/s, it forms an island-like shape, showing increased turbulent kinetic energy concentrated beneath the lances. Both transverse and radial vorticity diffusion within the molten bath are significantly influenced by the formation of impact cavities. The centroid tracking method is utilized to evaluate the overall sloshing dynamics of the furnace during the blowing process. Notably, the square furnace exhibits the largest oscillation amplitude, indicating pronounced dynamic instability. Fast Fourier Transform analyses of the centroid signal reveal that the dominant frequency of furnace oscillation predominantly lies within the range of 0 to 1 Hz.</p>