The microstructure, mechanical properties and corrosion resistance of Al-Mg-Si-Mn alloy with different contents of rare earth element La were studied by SEM, OM, tensile test (normal temperature/high temperature), bending test and intergranular corrosion test, and the effects of rare earth element La on the mechanical and corrosion properties of the alloy were analyzed. The results show that with the addition of La element, the as-cast microstructure of the alloy is gradually refined, the morphology of the second phase is improved, the thickness of the coarse grain zone of the profiles is reduced, and the mechanical properties and corrosion resistance of Al-Mg-Si-Mn alloy are improved. When La content is 0.2 wt. %, the grain refinement effect is the best, and the coarse grain zone is the thinest. When La content is greater than 0.2wt. %, the primary phase formed by excessive La interacts with the grain refiner Ti in the alloy, which reduces the number of heterogeneous nucleation cores, leads to grain coarsening phenomenon, and degrades the mechanical properties and corrosion resistance of the alloy.