In　order　to　explore　new　technologies　to　synthesize　the　CoSb3　type　thermoelectric　materials,　the　basic　technologies　of　preparing　CoSb3　powder　by　mechanical　alloying　were　investigated.　The　phase　transformations　and　crystal　size　of　Co-3Sb　powder　were　analyzed　by　X-ray　diffraction　(XRD).　The　shape　and　grain　size　of　CoSb3　powder　were　observed　by　scanning　electron　microscope　(SEM)　and　transmission　electron　microscope　(TEM).　The　results　show　that　the　single　phase　CoSb3　Powder　with　20-35　nm　nanocrystalline　was　prepared　successfully　by　milling　for　5　h　under　a　ball　to　powder　ratio　of　20:1　and　a　working　voltage　of　110　V　for　the　high-energy　mill.　It　is　considered　that　CoSb3　is　a　metastable　phase　in　long　time　high-energy　milling,　as　it　tends　to　decompose.　(c)　2006　Elsevier　B.V.　All　rights　reserved.