n-type　(Mg2Si1-xSbx)(0.4)-(Mg2Sn)(0.6)　(0　＜=　x　＜=　0.0625)　alloys　were　prepared　by　an　induction　melting　and　spark　plasma　sintering　method　using　bulks　of　Mn,　Si,　Sn,　Sb　as　raw　materials.　The　analyzing　results　of　the　structure　and　thermoelectric　properties　show　that　the　single-phase　(Mg2Si1-xSbx)(0.4)-(Mg2Sn)(0.6)　alloys　can　be　obtained　at　8wt%　excess　of　Mg　addition.　The　lattice　constant　increases　linearly　with　the　amount　of　Sb,　the　electrical　resistivity　rho　firstly　increases　and　then　decreases.　The　electrical　resistivity　rho　of　samples　(x　＜=　0.025)　shows　semi-conductor　behavior,　while　that　of　the　samples　(x＞0.025)　shows　the　metallic　behavior.　The　Seebeck　coefficient　alpha　firstly　increases　and　then　decreases　with　the　increase　of　x　value.　Compared　with　the　non-doped　sample,　the　thermal　conductivity　kappa　for　samples　(x　＜=　0.025)　decreases　and　that　of　the　other　samples　(x＞0.025)　increases.　The　ZT　value　for　(Mg2Si0.95Sb0.05)(0.4)-(Mg2Sn)(0.6)　sample　reaches　its　highest　value　of　1.22　at　773　K,　which　is　much　higher　than　that　of　the　non-doped　sample.