<p>The thermodynamic analysis of the reaction between the main phase in magnesium slag and NH₄Cl solutions was carried out, and the ions leaching behaviors of Ca, Mg, Fe, and Al in magnesium slag under room temperature and microwave conditions were compared. Meanwhile, the effects of parameters on the leaching rate of Ca and Mg were investigated under the microwave heating conditions. The experimental results show that, in 273.15–373.15 K, Ca₂SiO₄, CaSiO₃, Ca₂Fe₂O₅, and Mg₂SiO₄ might react with NH₄Cl solution, while MgSiO₃, MgO, Fe₂O₃, and Al₂O₃ are difficult to be leached. The leaching rates of Ca and Mg are 70.29% and 24.64%, respectively, when the conditions are 300 W of microwave power, 1:20 of solid-liquid ratio, 400 mL of 2 mol/L NH₄Cl solutions, and 90 min of leaching time. In addition, in the non-isothermal stage, the leaching process of Ca is changed from chemical reaction control to diffusion control, and the leaching rate of Ca gradually increases. However, the leaching process of Mg is always controlled by chemical reaction, and the leaching rate of Mg remains unchanged after the reaction reached equilibrium.</p>