This paper discusses the reversible process of ion exchange between soil and aquatic environment.On the basis of combining material balance with local ion exchange equilibrium,a mathematical model of 1-d convection,dispersian and ion exchange reaction taking place in soil column is built.Results obtained from ion exchange experiments by the authors and reported by previous literature all verified the model.As a consequence,the temporal-spacial distribution of ions A and B in two phases has been predicted.In view of current emphasis on quantitatively predicting the pollusion of soil and groundwater,this model would be helpful in practice.