To investigate the effect of catholyte shared by different membrane electrolytic cells on electrosynthesis of ammonium persulfate, the equivalent circuit models of two electrolytic cells with shared catholyte and separate catholyte were established and the pilot experiments were carried out with a cation exchange membrane (named PGN membrane) and the Al2O3 ceramic membrane. The model results showed that there appeared the bias ionic current from the low resistance electrolytic cell to the high resistance electrolytic cell with shared catholyte. The experimental results showed that the cathode current of the PGN membrane electrolytic cell was 56 A lower than its anode current with shared catholyte while the cathode current of the ceramic membrane electrolytic cell was 56 A higher than its anode current at the supply voltage of 5.3 V. And the current efficiency of PGN membrane and the ceramic membrane declined with their energy consumption increasing compared with those with separate catholyte. The model results showed a good agreement with those of the experiments. Therefore, it is necessary to consider the effect of shared catholyte by different membrane electrolytic cells on industrial electrosynthesis of ammonium persulfate.