Aluminum oxide is treated with calcium and magnesium coatings. After the alumina was treated with calcium and magnesium coatings, XRD analysis showed that there was v-type alumina with good adsorption properties on the surface of the three particles. Electron microscopy observation showed that the surface of the activated alumina was rougher after the coating, and the developed pore structure showed that it had Higher adsorption capacity. XPS analysis showed that calcium oxide (CaO) and magnesium oxide coating (MoO) were formed on the surface of the particles. After modification, the adsorbent was alkaline. BET measurement showed that the modification treatment increased the adsorption capacity of alumina. The specific surface area after modification is increased by more than 30% compared with that without modification. Static tests show that the fluorine adsorption capacity of modified alumina is significantly increased, and the fluorine removal effect is stable.