Abstract: Several parameters affecting slag splashing in LD converter have been discussed. Using paraffin and starch model, a simulated test about 30t converter has been made in laboratory and the modified Froude number was chosen as the main similar basis of the system. It was results that the optimized slag splashing parameters was obtained through data treatment. The nitrogen gas flow rate is about 8 500m³/h, the splashing time is of 3 min, and the lance height is of 0.8m. It is necessary to add MgO or carbon into the slag to adjusting slag composition. Also, it is difficult for the splashed slag condensing on the line when the slag temperature is much higher.