The　density　function　theory　been　used　to　calculate　the　electronic　structures　of　binary　and　doped　rare　earth　hexaborides　(REB6),　which　exhibits　the　large　density　of　states　(DOS)　near　Fermi　level.　The　d　orbital　elections　of　RE　element　contribute　the　electronic　states　of　election　emission　near　the　Fermi　level,　which　imply　that　the　REB6　(RE　=　La,　Ce,　Gd)　with　wide　distribution　of　high　density　d　orbital　electrons　could　provide　a　lower　work　function　and　excellent　emission　properties.　Doping　RE　elements　into　binary　REB6　can　adjust　DOS　and　the　position　of　the　Fermi　energy　level.　The　calculated　work　functions　of　considered　REB6　(100)　surface　show　that　the　REB6　(RE　=　La,　Ce,　Gd)　have　lower　work　function　and　doping　RE　elements　with　active　d　orbital　electrons　can　significantly　reduce　work　function　of　binary　REB6.　The　thermionic　emission　test　results　are　basically　accordant　with　the　calculated　value,　proving　the　first　principles　calculation　could　provide　a　good　theoretical　guidance　for　the　study　of　electron　emission　properties　of　REB6.　(C)　2017　Elsevier　B.V.　All　rights　reserved.