Abstract: The migration mechanism of lead ions in unsaturated loess under the action of electric field was studied in this paper. The adsorption type of lead ions on loess was determined through isothermal adsorption tests; A multi field coupled mathematical model for pollutant migration in unsaturated soil under the action of electric field was established based on a three-phase system of solid, liquid and gas. The model was numerically solved using COMSOL Multiphysics software, and the reliability of the model was verified through indoor soil column tests. The influence of various factors on pollutant migration was analyzed through parameter analysis. Research has shown that the Langmuir nonlinear adsorption model is more in line with the adsorption characteristics of loess particles for lead ions; The lead ion concentration and adsorption concentration in the height direction of the soil column increase with the increase of voltage, electrical permeability and ion diffusion coefficient. When the voltage increases by one time, the concentration and the adsorption concentration increase by about 11%, the electrical permeability increases by two times, the concentration and the adsorption concentration increase by about 10%, the ion diffusion coefficient increases by one time, and the concentration and the adsorption concentration increase by about 8%. When the maximum adsorption capacity of the soil increases by one time, the concentration decreases by about 33%, and the adsorption concentration increases by about 52%; Electrophoresis causes concentration enrichment at the negative electrode, and the higher the voltage, the more obvious the enrichment, but the effect of electrophoresis on adsorption concentration is not significant.