This paper used copper sulfate electrolytic process to carry on the cold simulation of rare earth molten salt electrolysis process.The experiment determined the distribution of electric field in the electrolysis process,and used the electric field model in COMSOL software to simulate the electric field distribution of the process. At the same time, comparing the results obtained experiments and simulation , the simulation results were matched with experiments. It is proved that the software can simulate the actual process of electrolysis; And used the electric field model in the software to simulate the electric field in the rare earth electrolysis cell. It is found that the simulation results are consistent with the test results of the actual operating conditions in the electrolytic cell. It ensured the correctness of COMSOL software when studied the rare earth electrolysis process. So, it provided a theoretical reference for the optimization and improvement of rare earth electrolysis cell.