In order to eliminate the inhomogeneous structure of as-cast GWZK94 alloys, the homogenization with the temperature range of 505-520 ℃ and the time range of 8-20 h were conducted by using resistance heating furnace. Optical microscope (OM), differential scanning calorimeter (DSC), X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), electron backscatter diffraction (EBSD), universal mechanical tester, and Vickers hardness tester were applied to investigate the microstructure evolution and mechanical properties. The as-cast alloy mainly consisted of the dendritic α-Mg matrix, lamellae with metastable stacking faults (SFs), Mg24(Gd, Y, Zn)5 which was a eutectic phase, bulk-shaped long-period stacking ordered (LPSO) phases (Mg12(Gd, Y) Zn), and a few RE-rich phases. During the homogenization, the lamellae and Mg24(Gd, Y, Zn)5 eutectic phases gradually dissolved into the matrix, and the volume fraction of bulk-shaped LPSO phases decreased while the lamellar-shaped LPSO phases grew into grains steadily, while some precipitated particle phases formed near the grain boundaries. At 520 ℃, triangle-shaped remelting eutectic phases appeared which indicated the over burning of magnesium alloy. Both ultimate tensile strength (UTS), tensile yield strength (TYS) and fracture elongation showed a tendency to correspond to microstructure evolution, and a more uniform hardness was investigated. The homogenization condition was optimized to be 515 ℃/16 h..