MgO-Cr2O3 refractories were prepared based on the formulation of 60%(in mass,the same hereinafter) fused magnesia chrome sand,27% chrome ore powder from South Africa,13% sintered magnesia,extra adding 1.5%,2%,2.5%,and 3% desiliconized ZrO2 micropowder,respectively,to improve the properties of MgO-Cr2O3 refractories.Effects of the ZrO2 additions on bulk density,apparent porosity,crushing strength,hot modulus of rupture,and resistance to RH degasser slag were investigated.The results show that:(1)introduction of ZrO2 improves the bulk density,cold crushing strength and hot modulus of rupture of the MgO-Cr2O3 refractories obviously;(2)ZrO2 reacts with CaO in the slag forming CaZrO3 with high density and high melting point,blocking pores and preventing the further slag penetration;meanwhile,the reaction consumes CaO,decreasing the basicity and increasing the viscosity of molten slag,thus increasing the slag resistance of the refractories.Therefore,take all properties into account,the optimal ZrO2 addition is 2.5%.