In this paper, microstructure of AL-Cu eutectic alloy is simulated by improving Nestler’s multiphase-field model. The exact physical parameters are used in multiphase-field model, and obtained the steady calculational results. In this numerical calculation, AL and AL2Cu are regard as two independent components. The eutectic microstructure is regard as an admixture of single phase α (AL) and single phase θ (AL2Cu). Using the model, steady eutectic layered growth is simulated, and the simulated results agree well with the solidification theory. At the same time, the stochastic noise is introduced, and eutectic free layered growth microstructure is simulated. The microstructure of primary dendritic crystal and pseudoeutectic is also simulated by enlarging the calculational interval scale, and obtained a better result.