Abstract: The effects of the addition of rare earth La（0.1wt%, 0.2wt%, 0.4wt%, 0.8wt%） on the as-cast microstructure and mechanical properties of 6082 aluminum alloy were investigated by SEM, EDS and XRD. The results show that the rare earth La can significantly refine the alloy grain, effectively regulate the second phase and improve the mechanical properties of the alloy. With the increase of rare earth La content in the alloy, the grain size of the alloy decreases first and then increases,and the best grain refinement effect is achieved when the mass fraction of rare earth La is 0.2wt%, and the tensile strength,yield strength and elongation of the alloy reach the highest of 181 MPa, 167 MPa and 5.43%, respectively, which are significantly better than those of the alloy without the addition of rare earth La（128 MPa, 87 MPa and 4.68%）. The addition of rare earth La can effectively modulate the elongated strip-like β-Al FeSi phase into π-like α-Al Si Fe phase, which greatly reduces the stress concentration and thus improves the mechanical properties of the alloy.