Large amounts of dust produced in basic oxygen steelmaking not only reduce the yield of metal, but also increases the dedusting load. Based on the different vapour pressure of Mn, Fe, V, Mo, disparate alloys were added into induction furnace with various carbon content, and different portions of mixed gas of CO2 and O2 were blown into the furnace. Through laboratory investigation of the production behaviour of dust in basic oxygen steelmaking, the dust production mechanism was studied. The experiments prove that the production of dust in basic oxygen steelmaking depends on both entrainment of the bubbles and evaporation of elements. As the reactions proceed, the dust particle size shows a tendency to become larger. With the increasing of CO2 blowing rate, the amount of dust produced by entrainment of the bubble increases, while which produced by evaporation of elements decreases, and dust size diminishes. Blowing a certain portion of CO2 into the bath not only contribute to the utilisation of CO2, but also reduce dust and obtain higher quality converter gas. The purpose of energy saving and consumption reducing can be implemented finally.