To provide essential data for an efficient utilization of vitrified bottom ash slag, the thermodynamic properties of the CaO-Al2O3-SiO2-FeOx-MgO-Na2O oxide system is highly required. As one of the related oxide subsystems, the equilibrium phase relations and liquidus of CaO-SiO2-FeOx-Al2O3 system is of great significance to interpret and predict the thermodynamic properties in multi-component oxide systems. In this paper, phase diagrams for the CaO-Al2O3-FeOx and SiO2-Al2O3-FeOx systems were calculated by using CALPHAD method with FactSage program. The liquid phase area changed with changing oxygen partial pressure from 1Pa to 10-3Pa and temperature from 1673K to 1773K. The equilibrium phase relations of CaO-Al2O3-FeOx and SiO2-Al2O3-FeOx systems were discussed.