Magnesium alloy is alloyed with rare earth elements (Re, Ca, Sr) because of its limit in using high-temperature condition. In this study, the influences of Zr and Zn on the aging behavior of Mg-Nd-Y alloy have been investigated. Magnesium alloys containing R.E elements need aging treatments. Specifically Nd, Y and Zr are used very often for high-temperature magnesium alloys. Various aging treatments were conducted at 200, 250 and 300℃ for 0.5, 1, 3, 6, 10 hours to examine the microstructure changes and mechanical properties at high temperature (150℃). Hardness and high temperature (150℃) tensile tests were carried out under various aging conditions in order to investigate the effects of aging treatments on the mechanical properties of Mg-3.05Nd-2.06Y-1.13Zr-0.34Zn alloy. The maximum hardness was 67Hv and it was achieved after aging at 250℃ for 3hours. The maximum tensile, yield strength and elongation in 150℃ were 237MPa, 145MPa and 13% at 250℃ for 3 hours, respectively. The strengths of Mg-3.05Nd-2.06Y-1.13Zr-0.34Zn alloy increased with aging time up to 3 hours at 250℃, which was attributed to the precipitation of a Nd-rich phase, a Zr- rich phase and Mg₃Y₂Zn₃.