Based on the several solute redistribution models, a more reasonable solute redistribution model is presented. The cellular states on the solid/liquid interface and the states of its neighboring cells possibly occurring during the grain growth are fully considered in the model, and different formulas are built for different cases. Firstly, the simulation result shows that the disadvantage of the original cellular automation (CA) model (its grain growth is controlled by solute distribution), in which the cells on the grain boundary are kept unsolidified all the time, is eliminated. Then, in order to verify the reliability of the new model, the new model is introduced into the CA model in which grain growth is controlled by Kurz-Giovanola-Trivedi model. The microstructure of the Al-4.7 wt%Cu ingot is calculated. The simulation results are in good accordance with experimental results in two aspects of microstructure morphology and concentration distribution.