In order to apply optimal design techniques or model-based control schemes to simulated moving bed (SMB) processes, the numerical model typically obtained by applying the finite difference method to the fixed-bed column is used. Such a model suffers from the computational load due to the numerical stability and may show low accuracy under the nonideal conditiond, where dispersion effects such as axial dispersion and mass transfer resistance are dominant. This work proposes a transition model of the SMB process that is free from the computational load and shows higher accuracy in predicting the system dynamics. The key factor is parametrizing the fundamental solution of the diffusion partial differential equation to approximate the transition behavior of the states. The simulation of the transition model is conducted on both linear and Langmuir isotherms, and the results indicate the superiority of the transition model over the conventional model in terms of both numerical accuracy and computation requirement especially under highly nonideal condition.