Abstract: The SiO₂ component of the traditional mold fluxes can easily been deoxidized by the Al contained in liquid high aluminium steel.So a series of mold fluxes containing lower SiO₂ was designed to solve this problem, and their viscosity-temperature curves and melting points were tested.The results showed that these viscosities and melting points are suitable to industrial application.The thermodynamic analysis and the steel-slag interfacial reaction experiment showed that the mold fluxes of which SiO₂ content is less than 6% can be called non-reactive mold powder.