The　optical　floating　zone　method　was　employed　to　fabricate　the　Samarium　hexaboride　(SmB6),　which　were　high-quality　single　crystals.　The　density　function　theory　was　used　to　calculate　the　electronic　structures　of　the　SmB6,　which　exhibits　the　large　density　of　states　near　Fermi　level.　And　the　d　electrons　of　Sm　element　contribute　the　electronic　states　near　the　Fermi　level,　which　imply　that　the　(100)　crystal　surface　has　a　highest　Sm　concentration　which　provide　a　low　work　function.　The　thermionic　emission　test　shows　that　the　effective　work　function　of　the　single　crystal　SmB6　on　(100)　crystal　surface　is　2.76eV.　The　SmB6　single　crystals　have　potential　application　prospects　as　a　hot　cathode.　(C)　2017　Elsevier　Ltd.　All　rights　reserved.