Modification agent is mainly used for protection of converter slag splashing,the slag are required to have a proper viscosity and refractoriness, reasonable slag content of MgO style is the key to the implementation of furnace protection by slag splashing. Adjusted to join a certain amount of modification agent, at the same time reduce the use of dolomite, reduce slag quantity, increase the content of MgO style in slag. Because of MgO style is high melting point mineral, melting point is 2800 ℃, the increase of MgO style content is in slag, the slag viscosity and improve the refractoriness, so the slag is easier with lining together, form effective protective layer of slag on the furnace lining, thus improve the lining life, reduce consumption of refractory material of per ton steel.