Abstract: According to the non-equilibrium solidification theory of the melt, the effects of basicity, MgO and FeO mass percentages on the initial precipitation temperature, precipitation amount and chemical compositions of spinel phase in CaO-MgO-Al₂O₃-SiO₂-Cr₂O₃-FeO-TiO₂ system, a basic component of the glass-ceramics prepared by stainless steel slag have been studied by using the thermodynamic database of Factsage 7.1. The results show that the mineral phases precipitated in the process of non-equilibrium cooling and solidification mainly include diopside, anorthite and spinel phases, among which diopside is the main phase. The spinel phase, precipitated at high temperature, is mainly composed of MgCr₂O₄ and FeCr₂O₄. At different degrees of basicity, the initial crystallization temperature of spinel rises with the increase of the mass percentage of MgO. When the w(C)/w(S) is 0.47 and the mass percentage of MgO is less than 10.52%, the precipitation amounts of magnesium-chromium spinel and iron-chromium spinel increase with the increase of the mass percentage of MgO. When the w(C)/w(S) is 0.47 and the mass percentage of MgO is over 10.52%, the precipitation amount of magnesium-chromium spinel increases while that of iron-chrome spinel gradually decreases. When the mass percentage of FeO is less than 7.57%, the precipitation amount of magnesium-chromium spinel and iron-chrome spinel increases with the increase of the mass percentage of FeO. When the mass percentage of FeO exceeds 7.57%, the precipitation amount of the magnesium-chromium spinel decreases and that of iron-chromium spinel increases with the increase of the mass percentage of FeO.