The effects of solidification condition and vibration on structure refinement were investigated for unidirectionally solidified Al-CuAl₂eutectic composites. Eutectic composites were unidirectionally solidified under vibration with different growth rates (R) and thermal gradient(G). The lamellar structure was varied according to growth condition (G/R ratio). For the structure refinement the effect of G/R was found out to be greater than that of vibration. The interlamellar spacing(λ) in this materials was varied with the growth rates(R) with "λ²R=constant" relationship.