There are many bottom-blown smelting furnaces in metallurgical industry.When oxygen or air sprays from the jet nozzle into the bottom of the furnace, the melting phase will be frozen and a hemispherical porous zone with a mushroom head shape will be formed around the nozzle.The mushroom head can pro-tect the jet nozzle and mitigate the liquid spray on the surface of melt.In order to analyze the formation process of a mushroom head in the bottom-blown smelting furnaces, a hydraulic experiment system was designed and the formation of the mushroom head was investigated by hydraulic experiment.The hydrau-lic experiment results show that the formation process is mainly divided into generating crushing genera-ting process and stable mushroom head generation process.The formation of stable mushroom head re-quires certain thermodynamic condition and water splash is more intense without a mushroom head than with a mushroom head.The size, porosity and diameter of the mushroom head are affected by the flow rate, temperature and heat capacity of the bottom-blowing gas and the temperature of the superheat and the physical parameters of the melt.