Abstract: Zn-Mg-Y and Mg-Zn-Y-Zr ingots with different chemical compositions were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The icosahedral phases were found in all alloys studied in present work under the as-cast conditions. There are nearly all quasicrystal phases with some MgZn2 Laves phase in a Zn-28.31Mg-13.80Y alloy (wt pct).After annealing at 400℃ for 8 h, the quasicrystal phases transformed to an fcc "W" phase in an Mg-5.57Zn-1.08Y-0.60Zr alloy (wt pct).