The General Rate (GR) model has been considered as the most comprehensive mathematical model which describes the mass transfer processes of the solute in the chromatographic column. But its numerical calculation is complicated and time consuming. In this work, the modified Equilibrium-Dispersive (MED) model which provides a simplified method to obtain the numerical solution of GR model is deduced according to the moment analysis result of the GR model. And the equivalence of the numerical results of the GR models and the MED model is also investigated. The results reflect that the numerical calculation of the GR model can be substituted by that of the MED model. (C) 2009 Elsevier Ltd. All rights reserved.