Taking Ce(NO3)3*6H2O and (NH4)2 CO3*H2O as raw materials, and adding a small amount of PEG600 as a dispersant, Ce2 (CO3)3*8H2O precursor was synthesized by rapid chemical precipitation, and after heat treatment, nano-CeO2 was obtained, XRD, DTA, TEM, BET and spectral analysis and characterization were carried out on the sample, and the CeO2 grain size was calculated by Gaussian algorithm according to slow scanning. The results showed that the precursor completely turned into CeO300 after roasting at 2°C, the particle size was about 10~20 nm, the grain size was 5.7 nm, the specific surface area was 111.68 m2/g, and the purity was >99.97%.