This experiment samples were analysed by DSC, colorimeter, XRD, SEM and other instruments to explore the effect of sintering system on the phase-separated opaque glaze and its effect mechanism in R2O-CaO-Al2O3-B2O3-SiO2 system. The results show that the change of heating-rate affects the diffusion and migration time of the components in the glaze, causing the size distribution, average particle size and volume fraction of the phase-separated droplets change, resulting the glazed surface exhibits opaque blue and white effects. Increasing the firing-temperature can promote the mutual diffusion of the components in the glaze, and the bright opaque glaze with whiteness ≥70% can be obtained in the range of 1 160-1 220 ℃. Higher firing- temperature tends to cause the pinhole defects in the glaze surface. The phase separation of the glaze melt occurs continuously under the interaction of thermodynamics and kinetics of glaze melt during the cooling process, meanwhile, the final composition, morphology and size of the phase-separated droplets are in a momentary equilibrium state during the cooling process. Therefore, the cooling process has an important effect on the phase-separated opaque glaze.