The　effects　of　Nd　on　the　tensile　properties　of　Mg-6Al　as-cast　alloy　were　studied.　Results　show　that　the　yielding　strengths　of　Mg-6Al-xNd　(x=0,　2,　4,　6;　mass　fraction)　alloys　at　room　temperature　and　175　degrees　C　increased　with　the　Nd　content　increasing　and　reached　the　maximum　value　at　the　content　of　6.0%Nd.　The　ultimate　tensile　strengths　and　elongations　of　these　alloys　at　room　temperature　and　175　degrees　C　reached　their　maximum　values　at　the　content　of　4.0%Nd.　Both　the　ultimate　strength　and　the　elongation　decreased　slightly　when　the　content　of　Nd　increased　from　4.0%　to　6.0%,　which　is　mainly　due　to　the　increase　in　the　brittle　phase　of　Al2Nd.　The　microstructure　analysis　indicates　that　Nd　exists　in　the　Mg-6Al　alloy　in　the　form　of　needle-like　Al11Nd3　phase　and　polygonal　Al2Nd　phase　and　the　amount　of　Al11Nd3　is　much　more　than　that　of　Al2Nd.　The　Al11Nd3　phase　precipitates　at　the　dendritic　and　grain　boundaries　resulting　in　the　obvious　refinement　of　the　interdendritic　space　and　grains.　The　improvement　in　tensile　properties　of　Mg-6Al-xNd　(x=2,　4,　6)　alloys　is　mainly　attributed　to　the　grain　refinement　strengthening　and　the　second　phase　strengthening　caused　by　the　Al11Nd3　phase,　which　is　concluded　from　the　mechanics　analysis　of　the　tensile　process　by　hard-soft　section　model　and　the　tensile　fracture　observation.