The technological process uses mixed chloride of rare earth metal as raw material, under low acidity condition, uses potassium permanganate as oxidizer to carry out fractional distillation. The purity of produced CeO2 reaches 99.99%. The ce content in the residual liquor reduces down to 0.5%. The process features high efficiency, high yield, low cost, and can be directly joined with current separation technology and is suitable for mass production.