The invention discloses a modifier for slag splashing protection of a converter and a using method of the modifier, belonging to the technical field of converter steelmaking. The modifier consists of the following components by mass: 18%-33% of Al2O3, 40%-60% of CaO, 0.5%-2.0% of FeO, 6%-13% of MgO, 6%-15% of SiO2 and the balance of impurities, wherein the impurities include phosphorus impurities, sulfur impurities and manganic oxide and the diameter of the particle of the modifier is 3-20mm. The using method of the modifier comprises the steps of adding 1.5kg-4.0kg of the modifier for each ton of steel through an overhead bunker of the converter when slag splashing protection begins, and adding 5kg-10kg of the modifier for each ton of steel for curing the slags after slag splashing protection is finished. The temperature of the slags is measured, the temperature at the slag surface is 1,200-1,350 DEG C, and molten iron is charged after scrap steel is added. The modifier has the advantages of lowering the temperature of the slags during the process of slag splashing protection and playing a role of curing the slags.