The invention discloses a casting blank oxidation resisting coating and a spraying method thereof. The casting blank oxidation resisting coating is characterized in that the casting blank oxidation resisting coating is composed of main components including silicon nitride or silicon carbide or silicon nitride plus silicon carbide and iron, and other components including one or more of Al2O3, SiO2, MgO and Cr2O3; the oxidation resisting coating is sprayed at high temperature in a powder electrostatic mode, a double-layer protection structure for a low melting point glass phase and a ceramic phase is formed on the surface of a casting blank in the heating process, oxidation of the casting blank by burner gas and corrosion of the casting blank by the low melting point glass phase can be effectively restrained, and the steel yield is remarkably improved.