The invention relates to a crystallizer casting powder for high-aluminum steel continuous casting. The casting powder comprises the following elementary components in percentage by weight: not less than15% but not more than 40% of CaO, not less than 3% but not more than 15% of SiO2, not less than 10% but not more than 20% of Al2O3, not more than 3% of MgO, not more than 3% of Fe2O3, not less than6% but not more than 15% of F, not more than 1.5% of Na2O, not less than 3% but not more than 10% of Li2O, not less than 5% but not more than 20% of BaO, not more than 5% of SrO, not more than 5% o B2O3, not less than 2% but not more than 15% of C, and the balance of impurities. The preparation method of the casting powder comprises the following steps of: calculating and weighing the required raw materials according to ratio ranges of the elementary components, mixing and uniformly smelting the mixture in an ore heating furnace, cooling, crushing, adding required carbon materials, carrying out fine grinding, and finally drying and granulating in a spray granule drying tower. The casting powder has the capability of reducing the reactivity of slag steel so that the performance deterioration of the casting powder caused by the reaction of the slag steel can be slowed, the interfacial tension of the slag steel is improved so as to prevent slag entrainment, excellent casting blank lubricating and heat-transfer controlling characters are ensured, the capability of absorbing Al2O3 inclusions is improved, and a high-aluminum steel casting blank which has excellent surface quality and high quality can be cast.