Abstract: The production of desilicated zirconia (ZrO₂=88.60%-96.90%) and stabilized zirconia (ZrO₂ ≥ 91.54%, MgO ≤ 5.39%) was successfully carried out in a plasma facility of 150kW. Factors, such as temperature, time and charge carbon, which affect the removal of silica from zircon were also studied. The desilicated zirconia can be utilized as the replacement of zirconia being made by chemical purifying method to produce the unchangeable diametric tundish nozzle (75% ZrO₂) for the use of continuous casting, according to the preliminary examination by steel works, the main characteristic values of this trial-product can meet the requirements of industrial production.