This paper studied the effect of Mg-Nd alloys on the ignition-proof performance of AZ91D magnesium alloy. The results showed that 0.5%Nd decreased the ignition point of alloy for about 20°C, but the ignition point could been multiplied with the adding of Nd element. When the content of Nd reached 5%, the ignition point increased about 40°C compared with AZ91D alloy. The ignition point reduced after the addition of 0.5%Nd can be attributed to the decrease of the solidus temperature and liquidus temperature. The further analysis indicated Nd and Al formed Al3Nd first, which consumed the content of Nd, so that the alloy didn’t have enough Nd to form Nd2O3 to protecting the alloy. The EDS analysis indicated when the addition of Nd reached 5%, competent Nd2O3 could be formed and compact oxide film which consisted of Nd2O3, MgO and Al2O3 was formed to prevent alloys from oxidation and combustion.