ABSTRACT Through visualization experiments, the macroinstability behaviour in the molten pool of the oxygen coal combustion melting and separation furnace was analysed by a physical simulation. In the experiment, images were acquired using a high-speed camera and an image processing system was used to track the gas-phase change in the local area of the molten pool and regular fluctuation of the molten pool in real time. Among them, bubble as the carrier of jet energy transfer and liquid level fluctuation. A close connection was observed between the local area bubble motion, jet behaviour, and macroinstability characteristics of the liquid level. The effects of different variables on the local stirring of the molten pool and overall macroinstability were compared. The developed ironmaking process parameters were optimized. The optimal immersion depth of the oxygen lance was 15 mm, while the optimal diameter of the oxygen lance was 4 mm.