In current research, a novel Al-Mg-Sc-Zr alloy was produced through conventional rolling and annealing process and achieved a high thermal stability, a high ultimate strength (UTS) of 501.7 MPa, a high yield strength (YS) of 320.4 MPa and a high elongation to failure of 21.6%. X-ray diffraction(XRD), electron backscattered diffraction (EBSD) and transmission electron microscope (TEM) were utilized to observe the microstructure of samples. As a result, complex effects of solute Mg atoms and precipitate of Al₃(Sc,Zr) precipitation promoted formation of microstructure with large lattice misfit, sub-grain and dispersive distributed Al₃(Sc,Zr) precipitation. The main mechanisms for observed high strength were found to be due to the solid solution of Mg and precipitate of Al₃(Sc,Zr) precipitation, theoretical strength is in agreement with experimental strength. The presence of bimodal grain structure which was first found in conventional rolling structure and Al₃(Sc,Zr) precipitation provided space for dislocation accumulation, improved the dislocation storage capacity of the alloy, and then directly increases the elongation of the alloy.