The invention relates to a preparation process of continuous casting slab high-temperature oxidation resistant coatings, which is characterized in that less than 120 meshes of powder, reductant containing carbon, inorganic binders, surfactants, suspending agents and the like with the compositions such as 25-55 wt% SiO2, 10-20 wt% Al203, 11-23 wt% MgO and the like are respectively grinded and mixed evenly, then water is used to be mixed and stirred sufficiently evenly, and finally the density of the coatings are adjusted within 1200-1500 kg/m3. The coatings can not only be sprayed onto continuous casting slabs at normal temperature, but also be sprayed onto high-temperature casting slabs, form continuous whole protective coating layers under the action of high temperature, effectively reduce temperature drop of the casting slabs and oxidation burning loss in even heating process of a heating furnace without changing original performance of matrixes, and effectively decrease dilution of alloying elements on the surfaces of the casting slabs. After the casting slabs are out of the heating furnace, natural spalling capability of the coating layers is strong, and oxidation matrixes of the casting slabs are smooth. Raw materials of the oxidation resistant coatings are easy to be obtained, and the coatings have low cost and simple preparation process and are adaptable to oxidation resistance for various steels when being heated at 700-1300 DEG C/ 2-8 hours.