Magnesium alloys are alloyed with rare earth elements (Re, Ca, Sr) due to the limited use of magnesium in high-temperature conditions. In this study, the influences of Zr and Zn on the aging behavior of a Mg-Nd-Y alloy were investigated. magnesium alloys containing R.E elements require aging treatments Specifically, Nd, Y and Zr are commonly used for high-temperature magnesium alloys. Various aging treatments were conducted at temperatures of 200, 250 and 300˚C for 0.5, 1, 3, 6, and 10 hours in order to examine the microstructural changes and mechanical properties at a high temperature (150˚C). Hardness and high-temperature (150˚C) tensile tests were carried out under various aging conditions in order to investigate the effects of an aging treatment on the mechanical properties of a Mg-3.05Nd-2.06Y-1.13Zr-0.34Zn alloy. The maximum hardness was 67Hv; this was achieved after aging at 250˚C for 3 hours. The maximum tensile, yield strength and elongation at 150˚C were 237MPa, 145MPa and 13.6%, respectively, at 250˚C for 3 hours. The strengths of the Mg-3.05Nd-2.06Y-1.13Zr-0.34Zn alloy increased as the aging time increased to 3 hours at 250˚C This is attributed to the precipitation of a Nd-rich phase, a Zr-rich phase and Mg3Y2Zn3.