This paper presents a study of the splashing phenomenon caused by the impingement of supersonic jets onto the slag metal molten bath under real oxygen steel-making conditions using numerical simulations. The validity of the mathematical model has been verified through different applications. The time-sequenced occurrence process and generation mechanism of splashing are revealed, and the splashing rate is determined with respect to lance height and operation pressure by combining the multifluid volume of fluid model with the blowing number theory. The results show that the generation of splashing is a result of the collective effects of the direct ejection of individual droplets and the tearing of "splash sheets" or "large tears". It is also found that the splashing process is unstable and normally irregular during the blowing, and the splashing is enhanced in terms of the tearing of splash sheets or large tears with declining lance height or increasing operation pressure.