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The microstructures and precipitated phases of as-extruded Mg-Al-Ca-xNd alloys with 0-1.76wt.% Nd were studied by OM, SEM and XRD. The mechanical properties of the alloys at room temperature and high temperature were also tested. Experimental results showed that the addition of Nd resulted in the formation of Al₂Nd and Al₁₁Nd₃phases in the matrix and the grain refinement in Mg-Al-Ca alloy, and the amounts of Al₂Nd and Al₁₁Nd₃ phases increase with the increase of Nd addition. The average grain size of alloys changed from 4.80 μm without Nd to 2.39 μm when added 1.76% Nd. The mechanical properties at room temperature were improved due to the precipitation of second phases and grain refinement. With increment of Nd, the tensile strength increased from 267 MPa to 304 MPa, the yield strength increased from 144 MPa to 203 MPa and the elongation decreased from 20.0 % to 16.9% at room temperature in these alloys. At 150℃, the tensile strength increased from 192 MPa to 229 MPa, the yield strength increased from 140 MPa to 159 MPa and the elongation decreased from 48.6 % to 29.3% with increasing Nd content.