The invention belongs to the field of steelmaking, and particularly discloses a fluorine-free slag modifier for preventing a ladle refining device from adhering slag, a preparation method and a using method. The slag modifier consists of active lime, bauxite and boric anhydride; and the slag modifier comprises the following chemical components in percentage by mass: 75 to 85 percent of CaO, 10 to 20 percent of Al2O3, 5 to 15 percent of B2O3, 0 to 8 percent of MgO, and the balance of impurities, wherein SiO2 is less than 7.0 percent, H2O is less than 0.05 percent, and the total amount of sulfur and phosphor is less than 0.01 percent. During use, in order to prevent a ladle from adhering the slag, the slag modifier is fed into the ladle in the later period of discharging steel from a steelmaking furnace, and in order to prevent an RH dip pipe or a CAS-OB dip cover and the like from dipping into the ladle device to adhere slag, the slag modifier is fed at a refining station. The slag modifier can effectively control the refining device from slag adhesion and improve the service life of a fireproof material, is favorable for reducing the contents of the sulfur, oxygen and impurities in the steel, and is simple to prepare and convenient to store, transport and use.