Polycrystalline　rare-earth　hexaborides　(NdxGd1-x)B-6　(x　=　0,　0.2,　0.6,　0.8,　1)　were　prepared　by　the　reactive　spark　plasma　sintering　(SPS)　method　using　mixed　powder　of　GdH2,　NdH2　and　B.　The　effects　of　Nd　doping　on　the　crystal　structure,　the　grain　orientation,　the　thermionic　emission　and　the　magnetic　properties　of　the　hexaboride　were　investigated　by　X-ray　diffraction,　electron　backscattered　diffraction　and　magnetic　measurements.　It　is　found　that　all　the　samples　sintered　by　the　SPS　method　exhibit　high　densities　(＞　95%)　and　high　values　of　Vickers　hardness　(2319　kg/mm(2)).　The　values　are　much　higher　than　those　obtained　in　the　traditional　method.　With　the　increase　of　Nd　content,　the　thermionic　emission　current　density　increases　from　11　to　16.30　A/cm(2)　and　the　magnetic　phase　transition　temperature　increases　from　5.85　to　7.95　K.　Thus,　the　SPS　technique　is　a　suitable　method　to　synthesize　the　dense　rare-earth　hexaborides　with　excellent　properties.