Abstract: g-8Al alloy was modified with different amounts of Nd(0-0.8wt%), and the effects of modification with Nd on microstructure and tensile properties of the alloy were studied. The results show that the growth morphology of α-Mg primary phase were changed because of modification with Nd, and dendrite α-Mg phases were branching developly, but the results of refining grains were not obvious. The eutectic microstructures of Mg-8Al alloy before modification with Nd was partially divorced eutectic, after modifing with Nd, the microstructure turned to fully divorced eutectic, and continuous net distribution before modification changed to discontinuous distribution.When the adding contents of Nd was 0.4wt%, the alloy had the beste tensile properties at room temperature, tensile strength, yield strength and elongation increased by 24%, 11% and 61%,respectively, and a little amounts of lath-shaped Al11Nd3 rare-earth phase appeared in the microstructure.