The effects of adding rare earth Cerium on Al-4.5Cu alloy microstructure, solidification range and volume changes in the solidification process are researched. Experiments show that rare earth Cerium will bring remarkable effects on the alloy microstructure, solidification and solidification shrinkage interval. When the quantity of rare earth Cerium is about 4 wt%, the solid-liquid two phase of Al-4.5Cu alloy will range from 640°C to 600°C. The grains of the alloy are refined, round. The volume shrinkage is only 68.6% of that without adding rare earth Cerium.