The invention discloses a preparation method of crisaborole. The method comprises the steps as follows: a compound shown in a formula I and alkali metal borohydride are subjected to a contact reaction, and a compound shown in a formula II is obtained; the compound shown in the formula II and a compound a are subjected to a contact reaction, and a compound III is obtained; or the compound shown inthe formula II and dihydropyran are subjected to a contact reaction, and a compound III is obtained, wherein the compound a is trimethylchlorosilane, tert-butyldimethylsilyl chloride or chloromethyl methyl ether; the compound shown in the formula III and an isopropylmagnesium chloride solution are subjected to a contact reaction, and a standby solution is obtained; then, the standby solution is added to a mixed solution of a compound b and a third organic solvent for a contact reaction, hydrochloric acid is added for a contact reaction, and crisaborole, namely, a compound shown in a formula IV, is obtained, wherein the compound b is 2-alkoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, triisopropyl borate or trimethyl borate.