This study aims to determine the effect of lime application on the adsorption-desorption of magnesium characteristics in the acid soil of honey pomelo orchard，and to clarify the effect of liming on the soil magnesium availability，which will provide a scientific basis for the improvement of acidic soil.The research carried out the isotherm adsorption test with soil culture test and the soil samples collected in the field lime improvement test，and carried out desorption test with 0.02 mol·L-1 NaNO3.The results showed that，(1)with the increase of lime dosage，soil pH and exchangeable base cations concentration increased，and the influence degree in different soil layers was 0～10 cm(L1)> 10～20 cm(L2)> 20～40 cm(L3)；(2)The Langmuir isotherm adsorption equation accurately described Mg sorption behavior in all soil samples(R2=0.957～0.999)，with the increase of magnesium concentration in the equilibrium solution，the adsorption amount of soil magnesium increased and the adsorption distribution coefficient(Kd)decreased.With the increase of the amount of lime application，the Kd increased and the ability of soil to fix magnesium became stronger；(3)With the increase of lime application，the desorption amount of soil magnesium first increased and then decreased，the order of its size was C2(1.8 mg·kg-1)>C3(3.6 mg·kg-1)>C1(0.9 mg·kg-1)>C0(0)，and the desorption rate showed a gradual decline；(4)The soil adsorption capacity of magnesium was positively correlated with pH，organic matter，exchangeable Ca2+，exchangeable Mg2+，and base saturation(P<0.05)，and was significantly(P<0.05)negative with exchangeable acid and exchangeable Al3+，and the desorption capacity is opposite to adsorption capacity.In summary，rational lime application can effectively improve soil acidity，and the amount of adsorption and desorption of magnesium，and finally increase soil magnesium availability.