Interfacial reactions of bulk MgCr2O4, MgO and re-bonded magnesia-chrome refractory with FeO-SiO2 based copper slag melt were studied under controlled oxygen partial pressure of atmosphere by the prediction of thermodynamically-stable phases and high-temperature reaction tests. At the interface between bulk MgCr2O4/the slag melt, the formation of spinel phase was mainly predicted. The microstructure observation revealed that the FeCr-Al-O layer with a large amount of Fe existed at the interface. At the interface of bulk MgO/the slag melt both the prediction and experimental results with SEM-EDS analysis indicated that（Mg, Fe）O solid solution and（Mg, Fe）2SiO4 phases were formed due to the mutual diffusion of Mg and Fe. Thermodynamic prediction and the experimental results well corresponded with each other qualitatively. The slag melt penetrated into pores existing around MgCr2O4 grains in the refractory.

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