In order to produce high-end steel with high clearness, it is important to control the composition change in the inclusions. Generally, the composition control of inclusions is carried out in the ladle treatment, however, the control of inclusions is very difficult because the simultaneous and complex reactions among the molten steel, the slag, alloying elements occurred. Many researchers have reported that the various inclusions were observed in industrial process such as pure Al 2 O 3 , MgO-Al 2 O 3 spinel, and the inclusions originating from slag. Those results indicate that the ladle refining process is not in equilibrium. Furthermore, the inclusions in the ladle showed various behaviors such as the flotation of deoxidation products to the slag phase, the entrapment of slag originated inclusions to the steel phase, and the agglomeration between the deoxidation products and the slag originated inclusions Since the behaviors of inclusions influence the amount and total composition changes of the inclusions in the molten steel, the simulation model with behaviors of inclusions is necessary to control the composition changes in the inclusions. In the present study, by using the brushed-up coupled reaction model, we simulated the changes of composition and amount of various inclusions under 210 ton of low alloyed steel during ladle treatment. And the effect of inclusions behaviors on the amount and the composition changes of various inclusions were investigated using the reported results.