Abstract: The process optimization of prepartion of chromium hydroxide by using sodium chromate carbonization mother liquor and the effect of particle size distribution of chromium oxide were studied.The influence of constant temperature and washing method of Cr（OH）3 on product quality was investigated.Effects of sodium chromate content on the morphology of Cr2O3 particles and the relationship between the carbonation rate of sodium chromate carbonization mother liquor and the particle size distribution of Cr2O3 under fixed calcination conditions was studied.Results showed that with the increase of carbonation rate of sodium chromate carbonization mother liquor，the constant temperature requiring for the maximum reduc tion rate of Cr（Ⅵ） decreased.The chromium hydroxide filter cake was washed for three times and then calcined.The mass fraction of sodium chromate after calcination was 13%~15%.The prepared Cr2O3 was similar to sphere and its particle size was uniform.The parameters of the product after washing and drying were in line with Chromium Oxide Green Pigment， GB/T 20785—2006.By increasing the carbonation rate of the raw material，the D50 of Cr2O3 particles increased，and the Cr2O3 was obtained with a D50 of 3.13 μm at a carbonization rate of 39.87%.The particle size distribution was a typical normal di stribution，and the characteristic particle size values met the technical requirements of high end chromium oxide green products.

Key words: sodium chromate carbonization mother liquor；chromium oxide；carbonization rate；size distribution