Interfacial reaction between refractory materials such as zirconia, magnesia and doloma brick, and the metallurgical slags of the CaO-SiO₂-MgO-CaF₂ system with varying CaF₂ content were investigated at high temperatures using various methodologies with static and dynamic modes. To figure out the corrosion mechanism due to interfacial reaction with the slag, the slag characteristics were examined in terms of flow temperature and viscosity and the corroded interface of zirconia, magnesia and doloma refractories were analyzed by SEM-EDS and EPMA. With an addition of CaF₂, three different layers were formed at the interface between slag and zirconia refractory. Furthermore, the corrosion of zirconia refractory was found to be accelerated with an increase of CaF₂ which facilitated the dissolution of intermediate compounds. The penetration of slag through the grain boundaries of MgO refractory is enhanced by increasing the content of CaF₂ due to an increase in the fluidity of slag in the dynamic mode. On the other hand, in the static condition, a dense Ca₂SiO₄ layer is formed at the hot face of magnesia-doloma refractory due to a reaction between silica in slag and lime in doloma, resulting in the protection of direct corrosion of refractory brick. However, the thickness of C₂S layer decreases with increasing content of CaF₂ due to an increase in fluidity of slag.