Abstract: A new opaque galze with separated phases was investigated. The chemical compositions of the glaze are SiO₂, B₂O₃, Al₂O₃, CaO, MgO, ZnO, K₂O, Na₂O, etc. The over-all opaque effect of this glaze comes from phase separations in it which indicated by SEM.The opacifying effects of this glaze are resulted from the different grain size exists in glaze due to phase separation, that was explained withvitreous theory on phase separation and optical opacifying principle.