Nanocrystalline　CoSb3　bulk　alloys　with　relative　density　of　91.3%-99.6%　were　successfully　prepared　by　mechanical　alloying　and　spark　plasma　sintering　(MA-SPS)　at　200degreesCsimilar　to600degreesC.　The　grain　sizes　were　measured　by　X-ray　diffraction,　and　fracture　appearance　and　crystal　structure　were　observed　by　SEM　and　TEM.　The　experimental　results　show　that　the　average　crystal　grain　sizes　of　bulk　CoSb3　samples　sintered　by　SPS　from　the　powder　with　20nm-35nm　crystal　grain　size　milled　by　MA　are　less　than　100nm.　The　cystal　size　of　the　bulk　CoSb3　decreases　with　the　sintering　temperature,　and　the　density　increases　with　the　sintering　temperature.　The　mechanism　of　preparing　nanocrystalline　bulk　is　that　mechanical　alloying　makes　the　powder　size　to　be　fine　to　nanometer　and　the　special　fast,　short　time　and　low　temperature　technology　of　spark　plasma　sintering　restrains　the　crystal　grain　to　grow　up.