Abstract: In order to research the microstructures and mechanical properties of Mg-Gd-Er-Zn wrought magnesium alloy under different states. Mg-Gd-Gd-Zn alloy was prepared by conventional metal mold casting, solution treatment, subsequently hot extrusion and ageing treatment, and was studied by using optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the as-cast microstructures of Mg-Gd-Er-Zn alloy consists of α-Mg matrix and second-phase (Mg, Zn)₃Gd phase which distributes around α-Mg matrix. After solution treatment, the lamellar long period stacking ordered (LPSO) structure appeared. During hot extrusion, the grain of this alloy can be refined dramatically. And subsequently aged, the nano β' phases were precipitated. Finally, the tensile strength, yield strength and elongation of the aged alloys at room condition reach 397.5 MPa, 359.0 MPa and 6.0%, respectively.