Abstract: A novel Al-5.8Mg-0.4Mn-0.25Sc-0.25Zr alloy was fabricated by conventional gravity casting. The effects of homogenization treatment on the microstructure, hardness and conductivity of the as-cast alloy were investigated. The optimum process parameters were determined, which is 450℃×4 h. After 4-pass rolling for total rolling reduction of 68.4% with variable temperature, the tensile strength and elongation of the alloy reach 513.93 MPa and 6.84%, respectively, and the strength is 1.78 times of that of the as-cast alloy, and the ductility is good, which greatly improves the mechanical properties of Al-Mg-Sc alloy.Homogenization at 450℃×4 h refines the grains of the as-cast alloy and a large number of fine and dispersed Al₃（Sc, Zr） particles are precipitated, which significantly improves the dislocation accumulation rate and inhibits the migration ability of grain boundary/subgrain boundary during the deformation process, and a fine subcrystalline structure with profuse dislocations is obtained that greatly improves the strength of the alloy. The strength of the alloy is also enhanced by the solid solution strengthening of high content Mg solute atoms and the precipitation strengthening of high density Al₃（Sc, Zr） nano-phase.