The cationic membrane electrolysis of potassium chromate and potassium dichromate crystallization were studied. The effects of current density, temperature, KOH concentration and K2CrO4 concentration on electrolytic process were investigated. The purity and yield were studied under different concentrations and conversions of potassium dichromate solution. The effects of stirring rate, cooling rate and seeds adding on the particle size distribution and crystal morphology were researched. The results showed that, the optimum condition was current density of 0.25 A/cm2, electrolysis temperature of 80℃, KOH of 50 g/L and K2CrO4 of 400 g/L. The purity of crystal is not less than 99.8% when the conversion rate of K2Cr2O7 more than 90%. The optimize conditions of crystallization process were K2Cr2O7 initial concentration of 500 g/L, stirring speed of 300 r/min, cooling rate of 0.5℃/min, no seed adding. Product was completely in conformity to GB 28657-2012.