By a grid of tetrahedralization, this paper performs numerical simulation on sphere models and combination models by using the three-dimensional finite element method. The results reveal the spatial distribution of electric anomalies produced by the models, and can do volumetric sounding without adding too much work. Combined simulation of resistivity and polarizability attains high accuracy and good stability. And the simulation results of copperplate and copper billet by physical experiments performed in water channels verify the feasibility and validity of the multiple-electrode-distance central gradient sounding. These simulation results are of great significance for application of the method and follow-up inversion calculation.