Abstract: Ceramic foam filter(CFF) made from partially stabilized zirconia(PSZ) is a kind of ideal filter material used to purify melted casting steel and high temperature alloys for improving quality of the cast.The ceramic foam filter that is made from Mg-PSZ powder with the additions of CeO₂ or the rare earth abounding with CeO₂ has excellent high temperature performance.In this paper,the effect of the stability phase in PSZ on the high temperature performance is deeply discussed,on the base of the CFF's crystal phase constitution and morphology analysis by means of modern analytic methods such as SEM and XRD spectra.