Abstract: To explore the effect of heavy metal Pb²⁺ intrusion on the deformation characteristics of red clay, relative density tests and consolidation tests are conducted on red clay specimens contaminated with different Pb²⁺ concentrations, the research object is the red clay of Guilin. The results show that the relative density of red clay increases with the increase of Pb²⁺ concentration and the corresponding pore ratio also increases; the results of consolidation test show that the compression coefficient of red clay after Pb²⁺ contamination is larger at low concentration and low pressure than that at high concentration and low pressure, which indicates that the invasion of Pb²⁺ weakens the ability of red clay to resist deformation; The compressive modulus of red clay after contamination with 0.05 mol/L Pb²⁺ solution at 50 kPa is reduced by 67.2% compared to uncontaminated red clay. In addition, the Zate potential test combined with the Gouy-Chapman diffusion bilayer theory shows that the potential of the red clay diffusion layer decreases after Pb²⁺ contamination, which is due to the increase in the valence and concentration of Pb²⁺ as a result of the osmotic pressure and inter-ionic forces that cause Pb²⁺ to enter the diffusion layer, so the thickness of the red clay diffusion layer is decreasing as the Pb²⁺ concentration increases. The potential value of the red clay decreases with the increase of Pb²⁺ concentration and the curve gradually flattens out, and the decrease of the diffusion layer thickness also flattens out.