Abstract: The influence of element Nd addition on the microstructure and mechanical properties of as-cast Mg-5Zn-2Al alloys ( with content of Nd was 0.3wt%,0.6wt% and 0.9wt% respectively) had been investigated by using metallographic microscope,electronic universal matrials testing machine,scanning electron microscopy and X-ray diffraction.The results show that,for the as-cast Mg-5Zn-2Al alloys,the main phases were α-Mg matrix phase,τ-Mg32(Al,Zn)49 phase and AlNd phase.With increasing the addition of Nd in the alloys,the amount of AlNd phase increased.The mechanical properties exhibited the trend of arising first and descending later.When the content of Nd was 0.3wt%,the tensile strength was the highest,with the value about 204 MPa.The elongation reached the highest,with the value about 11.125%.