The　microstructure　and　strengthening　mechanisms　of　as-cast　Mg-6Al-6Nd　alloy　were　studied.　The　results　show　that　the　addition　of　6　wt.%　Nd　into　Mg-6Al　alloy　leads　to　the　precipitation　of　Al(11)Nd(3)　and　Al(2)Nd　phases　and　decrease　in　the　content　of　Al　solid　soluted　in　Mg-Al　matrix.　The　volume　fractions　of　Al(11)Nd(3)　and　Al(2)Nd　phases　are　3.64%　and　0.34%,　respectively.　Compared　with　Mg-6Al　alloy,　the　ultimate　strength,　yielding　strength,　and　elongation　of　Mg-6Al-6Nd　alloy　at　room　temperature　and　175　degrees　C　are　enhanced　in　some　degrees.　The　strengthening　mechanisms　of　Mg-6Al-6Nd　alloy　are　mainly　composed　of　solid　solution　strengthening　of　Al　solid　soluted　in　Mg-Al　matrix　and　grain　refinement　strengthening,　dispersion　strengthening,　and　composite　strengthening　brought　by　the　precipitation　of　Al(11)Nd(3)　phase.　The　composite　strengthening　includes　the　load　transfer　from　the　matrix　to　Al(11)Nd(3)　phase　and　the　enhancement　of　dislocation　density　due　to　the　geometrical　mismatch　and　thermal　mismatch　between　the　matrix　and　Al(11)Nd(3)　phase.