Mg3Sb2-based　thermoelectric　materials　have　poor　electrical　conductivity　which　is　the　key　to　limit　thermoelectric　performance　that　need　to　be　solved.　Herein　we　tuned　the　carrier　concentration　of　Mg3Sb2-based　materials　via　Ag　doping　at　the　Mg　sites　(at　two　distinct　crystallographic　sites)　to　enhance　the　electrical　performance.　Mg3-xAgxSb2　(0　＜=　x　＜=　0.05)　has　been　prepared　successfully　by　vacuum　suspension　smelting　plus　Spark　Plasma　Sintering　technique.　Using　the　vacuum　suspension　smelting　plus　Spark　Plasma　Sintering　method,　we　proved　that　Ag　doping　can　precisely　tune　the　electrical　transport　properties　and　accordingly　enhance　the　power　factor.　Moreover,　the　Ag　doping　leads　to　a　low　lattice　thermal　conductivity　due　to　phonons　scattering,　and　the　maximal　thermoelectric　figure　of　merit　ZT　for　Mg2.96Ag0.04Sb2　reaches　0.66　at　773　K.　(c)　2018　The　Chinese　Ceramic　Society.　Production　and　hosting　by　Elsevier　B.V.