With fused magnesia as aggregate,fused magnesia powder,sintered magnesia powder and carbonaceous material as matrix material,some anti oxidants,promoters,wetting agents and composite binders are added,and proper particle gradation is selected,a large surface mending material for converter with dense and long life is developed,which can meet the requirements of the site.In this paper,the particle size distribution,the type and particle size of carbonaceous materials and the amount of their addition,as well as the type and amount of the promoters and wetting agents were studied.The results show that the particle size distribution is better when the ratio of coarse,medium and fine is 20∶40∶40.The composite use of carbonaceous materials is conducive to the improvement of various properties of the mending materials.The combustion promoter can promote the carbonization of carbonaceous materials such as asphalt and shorten the sintering time.The wetting agent can reduce the dust during production,which is beneficial to environmental protection.In addition,it can enhance the combination of magnesia and asphalt,which is conducive to the improvement of the high temperature performance of the mending materials.