The　single-phase　n-type　Mg-2(Si0.4-xSbxSn0.6)　(0　＜=　x　＜=　0.025)　solid　solutions　were　prepared　by　an　induction　melting　and　Spark　Plasma　Sintering　method　using　buck　of　Magnesium,　Silicon,　Tin　and　Antimony.　The　unique　multiple　nanostructures　of　samples　containing　nanoscale　precipitates　and　mesoscale　grains　are　formed　by　the　non-equilibrium　preparing　technique,　resulting　in　remarkably　decreasing　of　lattice　thermal　conductivities,　particularly　for　samples　with　the　nanoscale　precipitates　having　the　size　of　20-30　nm.　Meanwhile,　the　electrical　properties　were　increased　by　Sb-doping.　The　thermoelectric　performance　of　Sb　doped　samples　with　the　nanostructures　are　remarkably　improved,　and　the　dimensionless　figure　of　ZT　for　Mg-2(Si0.38Sb0.02Sn0.6)　sample　shows　highest　value　of　1.30　at　773　K,　which　is　very　much　higher　than　that　of　the　non-doped　sample.　(C)　2014　Elsevier　B.V.　All　rights　reserved.