Magnesium （Mg） leaching is one of the main reasons for magnesium deficiency in yellow soils.Indoor soil column leaching experiments were conducted to explore the mechanisms and principles by which nano-Mg fertilizer reduces Mg leaching,with the aim of providing a basis for using nano-Mg fertilizer to alleviate Mg leaching in yellow soils.The results show that after the application of an equivalent amount of Mg fertilizer （2.4 g/kg Mg O）,nano-Mg（OH）₂treatment significantly reduced the concentration of Mg²⁺ and the amount of Mg leaching in the leachate,with a 25.93%reduction in Mg leaching compared to conventional Mg（OH）₂;MgSO₄ treatment exhibited a strong migration and release capacity in the soil.Analysis of Mg²⁺ adsorption and the net forces acting on soil particles revealed that nano-Mg fertilizer treatment enhanced the soil particles'adsorption capacity for Mg²⁺ and moisture,and increased the net force at a distance of 1nm between soil particles,thereby reducing the leaching of Mg.Considering the characteristics of Mg²⁺ leaching,moisture migration,adsorption capacity,and micro-properties,the application of nano-Mg（OH）₂ is an effective measure to reduce soil magnesium leaching.