To investigate the influence of cooling rate on the solidification structure of Al-Cu binary alloy, the ingot of Al-6%Cu alloy was produced by the wedge-shaped copper mode casting. The results indicate that when the cooling rate decreases from 100 K/s to 2 K/s, the grain morphology transformation of ingot is as follows: columnar grains→mixing of columnar grains with equiaxed grains→equiaxed grains. Meanwhile, the width of columnar crystal at the ingot edge increases from 244.7 μm to 408.2 μm, the average grain size of equiaxed crystal at the ingot core decreases from 629.8 μm to 152.8 μm, and the average dendrite arm spacing increases from 10.1 μm to 52.8 μm. The parameters A and n of Al-6%Cu alloy in the empirical formula of average dendrite arm spacing and cooling rate are 78.75 and 0.41, respectively. When the cooling rate decreases from 100 K/s to 25 K/s, the morphology of eutectic Al₂Cu changes from skeletal to lamellar, and α-Al near the eutectic Al₂Cu is cellular. With the cooling rate increases from 2 K/s to 100 K/s, the hardness of Al-6%Cu alloy is increased from 618 MPa to 726 MPa.