Nanostructure　materials　exhibit　different　properties　from　those　of　corresponding　bulk　substances,　the　decrease　in　the　grain　size　of　the　material　leads　to　a　drastic　increase　in　the　density　of　grain　boundaries,　which　brings　out　a　significant　reduction　in　thermal　conductivity,　k,　and　so　improve　the　value　of　thermoelectric　figure-of-merit,　ZT.　But　the　decreased　grain　size　reduces　the　electrical　conductivity　and　Seebeck　coefficient　at　the　same　time.　Based　on　the　above　reasons,　a　novel　method　of　in-situ　spark　plasma　sintering　(SPS)　is　used　to　synthesize　CoSb3-based　Skutterudite　compounds　with　nano/micro-meter　grains　by　controlling　the　grain　size　of　raw　materials,　and　the　thermoelectric　properties　are　studied　systematically.　The　results　indicate　that,　the　ratio　of　electrical　conductivity　and　thermal　conductivity　is　optimized,　and　a　relative　high　Seebeck　coefficient　is　obtained　at　nano/micrometer　scale.　As　a　result,　the　dimensionless　figure　of　merit　ZT　is　greatly　improved　for　CoSb3,　and　La0.3FeCo3Sb12,　the　highest　value　of　ZT　of　0.34　and　0.72　is　obtained　at　700K　for　CoSb3　and　La0.3FeCo　3Sb12　Skutterudite　compound,　respectively.　©　2006　IEEE.