In this study, a two dimensional model for prediction of microsegregation in solidification was suggested on the basis of the previous one dimensional model. Especially, for the growth of a secondary arm, a simple and effective mathematical function was established to show the growing pattern. The solute diffusion in the solid phase was calculated by the finite difference method(FDM). The solid-liquid interface movement was considered to be in local equilibrium state indicated by the phase diagram. The experiments for an unidirectional solidification of Al-4.9wt.%Cu binary alloy were carried out in order to examine the reasonability and feasibility of this model. The concentration profile of solute and eutectic fraction predicted by the simulation agreed well with those found from experimental works. According to the results, it was believed that the pattern function introduced in this study was reasonable for the prediction of a microsegregation in dendritic growth.