Diffusion is an important mechanism for many processes including diagenesis and solute transport in sediments and groundwater. Multi-ion system is common in practical engineering, but the influence of electrostatic effect on diffusion process caused by ion charge has been neglected in previous studies, and the interaction between ions has not been embodied in the diffusion model. In this paper, based on the classical Fick Law, a multi-ion diffusion model considering diffusion potential was proposed by derivation with the aid of electrical neutrality constraint, in which the diffusion potential effect caused by the electrostatic between ions was considered. The finite element software COMSOL Multiphysics was occupied to conduct a series of numerical simulations to determine the influence of diffusion potential. The results showed that the diffusion potential accelerated the diffusion of cations and inhibited the diffusion of anions. When the anionic diffusion coefficients kept the same, the acceleration effect of the diffusion potential on ions increased with the decrease of the cation diffusion coefficient. When the diffusion coefficients of anions and cations in solution were constant, the acceleration effect of diffusion potential on ions movement increased slightly with the increase of ion valence.