Controlling conditions for inclusion plasticization were calculated by FactSage, and the steel/slag reaction equilibration time was determined by pre-equilibrium experiments. Laboratory experiments with different top slags were carried out in 90 min, and industrial tests were performed based on the results of calculation and laboratory experiments. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used to determine the morphology and composition of inclusions in tire cord steel. It is found that the shape of in-clusions can be controlled well, and the composition of inclusions varies in the industrial test as the following transformation route: MnO-Al2O3-SiO2→CaO-Al2O3-SiO2→MnO-Al2O3-SiO2. Inclusion plasticization can be achieved by controlling the binary basicity of top slag (CaO/SiO2 by mass) around 1.0 and the (Al2O3) content in top slag below 10wt%. Under these controlling conditions in the industrial test, almost all of inclusions in the wire rods achieve plastic deformation. Controlling conditions for inclusion plasticization were calculated by FactSage, and the steel / slag reaction equilibration time was determined by pre-equilibrium experiments. Laboratory experiments with different top slags were carried out in 90 min, and industrial tests were performed on the results of calculation and laboratory experiments. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used to determine the morphology and composition of inclusions in tire cord steel. It is found that the shape of in-clusions can be controlled well, and the composition of inclusions varies in the industrial test as the following transformation route: MnO-Al2O3-SiO2 → CaO-Al2O3-SiO2 → MnO-Al2O3-SiO2. Inclusion plasticization can be achieved by controlling the binary basicity of top slag (CaO / SiO2 by under these controlling conditions in the industrial test, almost all of inclusions in the wire rod s achieve plastic deformation.