In the converter steel making processing a large amount of molten steel slag is produced when smelting in the BOF. slag stopping plugs are cone shapes with slots and its density leads to float at the interface between the liquid steel and slag in the furnace. The slag stopping plug is inserted into the tap hole toward the end of the tapping operation by slag stopping plug dispatching machine to block slag inflow ladle, the performance can be increased to 96% slag layer less than 40 mm. the new technology reduced the energy consumption reduced the molten steel temperature loss increased the steel making operation security.