Abstract: In order to solve the common problem of Al₂O₃ inclusion modification in aluminum deoxidized steel,the deoxidation of steel by Al-Mg alloys was explored and practiced.Al-Mg deoxidation can achieve slightly better result than that of aluminum deoxidization.The oxygen activity after Al-Mg deoxidization is less than 10×10^-6,and the inclusion rating is less than 1.0.Compared with aluminum deoxidization,the numbers of inclusions larger than 30 μm and sulfide inclusions in Al-Mg deoxidized slab and sheet has been significantly reduced.The magnesium content in Al-Mg alloys increases from 5% to 7.5%,the inclusions in steel decreases significantly after deoxidization.The Al₂O₃-MgO and Al₂O₃-M_xO_y-MnS-CaS composite inclusions gradually form in the deoxidization process of Al-Mg alloys,and then float up to remove them,which reduces the damage of the aluminum-deoxidized strip-like Al₂O₃ inclusions,and the inclusions in steel become small.At the same time,the magnesium vapor bubble adsorbs inclusions during the floating process,then reduces the number of inclusions and clean liquid steel.