Abstract: To explore the adsorption behavior of magnesium in ionic rare earths during the leaching process of magnesium sulfate, the adsorption law of magnesium on the surface of ionic rare earth soil and the distribution and transformation of magnesium forms in the soil after adsorption were studied through adsorption kinetics and isothermal adsorption experiments. The experimental results showed that the adsorption of magnesium by ionic rare earth soil was single-layer adsorption and mainly relied on chemical adsorption; according to thermodynamic calculations, the adsorption process was spontaneous, accompanied by certain thermal effects; further analysis of its occurrence forms revealed that its main forms in soil were exchangeable and acid soluble states. Their content changes before and after soil adsorption were influenced by the pH value of the solution, with exchange magnesium being affected to a greater extent.