The mechanism of CaSO4 reclaiming sodic soils can provide theoretical basis for the field application of it's substitutes,including Desulphurization gypsum,fly ash,phosphorus gypsum,and so on.A multicomponent solute transport equations in which considering ion adsorption-exchange and dynamic changes of soil hydraulic conductivity was constructed by soil column experiment in this paper,and the UNSATCHEM software was used to simulate and predict the ion movement in the process of reclaiming the sodic soils with CaSO4.Four treatments were designed in the experiment,and the concentration of CaSO4 were 0.5,1,1.5,2 g/L respectively.The results indicated that: the adsorption-exchange reaction between the sodium in soil colloid and calcium in soil solution,were carried through in the process of reclaiming the sodic soils with CaSO4,and the multicomponent solute transport model could simulate the process by rule and line,including the movement of calcium and sodium in soil solution,adsorption-exchange between the sodium in soil colloid and calcium in soil solution;At the same time,it was not a short-term process that sodic soils reclaimed with CaSO4,the model of applying CaSO4 in batches could decrease the accumulation of soil salts and promote the dissolution of CaSO4 and this mode was better than that of applying CaSO4 only once.