Abstract: A series of triaxial permeability tests on phosphogypsum leachate, dry density tests and chemical constituent tests on soil are carried out in order to investigate the change of physical properties of soil using different test methods. The test results show that after the permeation process of phosphogypsum leachate entering the soil pore space, the acidic liquor will react with the constituents in the soil, and these chemical reactions lead to the physical property change of soil. The important changes are as follows: (1) the permeability coefficient of soil decreases in a power function mode with the increase of seepage time; (2) after the permeation process of phosphogypsum leachate, the dry density of soil decreases from the bottom up in the soil sample, and the pH value of permeation liquor increases. In addition, when the permeability coefficient of soil decreases to a value (very small) with the increase of seepage time, a natural anti-seepage layer is formed in soil, and the natural anti-seepage layer can prevent the development of the acidic liquor permeation in soil and the further erosion of soil by acidic liquor.