The structure, morphology and size distribution of phases in the Mg-Zn-Y magnesium alloys have very important effects on their mechanical properties. In this paper, the compound powders of Mg-Zn-Y phases were obtained from as cast and as aged Mg-6.0Zn-1.2Y and Mg-6.0Zn-0.6Zr-1.0Y magnesium alloys respectively by using of electrolysis extraction technology. Then several tests, such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion X-ray detector (EDX), were performed to investigate the structure and morphology of these compound powders. The results proved that picric acid - acetic acid - ethanol electrolyte was useful than DDTC-CAS-carbinol electrolyte in the electron extraction for Mg-Zn-Y magnesium alloys. The XRD results showed that the Mg3Y2Zn3, Mg10Y2Zn, Mg3YZn6, Mg-Y-Zn quasicrystal phases were obtained from Mg-6.0Zn-1.2Y magnesium alloy, and Mg3Y2Zn3, Mg10Y2Zn, ZrO2 phases were obtained from Mg-6.0Zn-0.6Zr-1.0Y magnesium alloy. The analyses of morphology and size distribution of these phases were put forth in this paper.